The research team, led by Guido Bocchino of the Catholic University of the Sacred Heart in Rome and including internationally recognized infection specialists such as Javad Parvizi, conducted what is known as an umbrella review. Rather than analyzing individual patient studies, this approach synthesizes existing systematic reviews and meta-analyses, offering a bird’s-eye view of where the published evidence converges and where it falls apart. The researchers searched major bibliographic databases in December 2025, following the PRISMA 2020 reporting guidelines, and ultimately included nine reviews: three systematic reviews and six systematic reviews with meta-analyses. To guard against the double-counting that plagues this type of synthesis, they built a citation matrix of all primary studies and calculated a corrected covered area of 9.4 percent, indicating moderate overlap among the reviews, a finding that shaped how cautiously they interpreted the aggregated numbers.

The headline statistic is striking in its variability. Reported prevalence of culture-negative periprosthetic joint infection ranged from 11.0 percent to 63.6 percent across the included reviews, with a mean of 33.6 percent and a median of 32.5 percent. In other words, depending on which review you consult, somewhere between one in nine and nearly two in three prosthetic joint infections fail to yield a positive culture. The authors attribute this wild spread to differences in patient populations, diagnostic definitions, microbiological workflows, and pre-analytical factors, meaning everything that happens to a specimen before it reaches the culture plate. One large quantitative review reported culture-negative proportions of 38.7 percent across 30 studies, while another meta-analysis found just 11 percent, a gap that underscores how much case mix and laboratory protocol can shift the apparent burden of the disease.

Among the factors driving culture negativity, one stood out repeatedly: prior antibiotic exposure. When patients receive antimicrobial therapy before surgical samples are collected, the drugs suppress bacterial growth in culture even though the infection persists. The reviews that quantified this risk factor reported antibiotic pretreatment in the range of 53 to 64 percent of culture-negative cases, lending strong support to a long-standing principle of antimicrobial stewardship: whenever clinically feasible, antibiotics should be withheld until diagnostic specimens have been obtained. The review also found that culture-negative infections were reported more frequently in the knee than in the hip, accounting for 64.1 percent of cases in the subset of data where joint-specific breakdown was available, and that most studies relied on the Musculoskeletal Infection Society criteria to define the condition, with smaller numbers using Infectious Diseases Society of America or International Consensus Meeting definitions, a patchwork that itself contributes to the heterogeneity.

Into this diagnostic vacuum has stepped a new generation of culture-independent molecular tools, and the umbrella review devoted considerable attention to their performance. Five of the nine included reviews evaluated molecular diagnostics, with next-generation sequencing approaches dominating the landscape. Metagenomic next-generation sequencing, which sequences all genetic material in a specimen without targeting specific organisms, appeared in four of the five molecular-enabled reviews, while targeted sequencing, PCR-based assays, and 16S rRNA sequencing each featured in one. Importantly, no single specimen type emerged as sufficient on its own: synovial fluid, periprosthetic tissue, and sonication fluid, the liquid produced by bathing a removed implant in ultrasound to dislodge biofilm bacteria, were all recurrently evaluated, often in combination, reflecting the understanding that molecular yield depends heavily on sampling strategy.

The diagnostic accuracy figures are impressive on paper. Where meta-analytic estimates were available, pooled sensitivity for molecular methods ranged from 0.81 to 0.93, and pooled specificity ranged from 0.92 to 0.97. In a direct platform comparison, metagenomic next-generation sequencing achieved a sensitivity of 89 percent and a specificity of 92 percent, while targeted next-generation sequencing traded a slightly lower sensitivity of 84 percent for a higher specificity of 97 percent. But the review is equally clear about the caveats. Raw pathogen detection rates among culture-negative cases varied enormously, from 9 percent to 100 percent across individual studies, with pooled summaries clustering around 52 to 54 percent. One review reported shotgun metagenomics detecting pathogens in 43.9 percent of cases while citing upper estimates near 82 percent for sequencing and 90 percent for synovial PCR in selected datasets. The overall false-negative proportion across the evidence base was 21.2 percent, meaning roughly one in five infections still slips past even the most advanced molecular assays.

Perhaps the most revealing finding concerns what molecular testing actually finds when cultures fail. In the one review that detailed post-molecular pathogen attribution, a remarkable proportion of culture-negative infections, around 46 percent, turned out to be fungal, predominantly Candida species, and the assays detected fastidious or atypical organisms including mycobacteria, Cutibacterium acnes, Brucella, and Coxiella burnetii. These are organisms that either grow slowly, require special culture conditions, or are suppressed by prior antibiotics, and their detection supports a conclusion that has been gaining traction in the field: culture-negative status usually reflects microbiological blind spots rather than the absence of any pathogen. Many infections that initially fail to grow in culture later become culture-positive on repeat sampling, suggesting that the true culprit was simply missed the first time around.

Treatment of these infections remains an exercise in empiricism. Because no organism is identified, antibiotic selection relies on guesswork rather than culture-guided targeted therapy. The review found that two-stage exchange, in which the infected implant is removed, an antibiotic-loaded spacer is placed, and a new prosthesis is implanted only after a course of antibiotics, was the most frequently described surgical strategy, accounting for 68.0 percent of the 2,336 extractable procedures across three reviews. Debridement with implant retention accounted for 21.7 percent, and one-stage exchange for 10.3 percent. Vancomycin and cephalosporins were the most commonly mentioned agents, typically providing broad Gram-positive coverage with additional Gram-negative activity, and systemic therapy after revision was often reported as approximately six weeks. Yet dosing, duration, and spacer composition were so inconsistently reported that the authors could not determine whether a two-week antibiotic holiday between stages improves outcomes, a question that recent consensus recommendations have addressed by suggesting continuous therapy may be preferable, particularly for immunocompromised patients.

Outcomes add another layer of complexity. The largest extractable dataset reported an overall failure rate of 19.0 percent for culture-negative infections, with a 95 percent confidence interval of 17.1 to 20.9 percent, while another review found pooled infection control of 79.2 percent. Other syntheses reported treatment success ranging from roughly 70 to 100 percent after two-stage exchange, a spread so wide that direct comparison becomes nearly meaningless. The authors attribute this to inconsistent outcome definitions, differing surgical protocols, and follow-up durations that ranged from three months to ten years. Methodological quality, assessed with the AMSTAR 2 instrument, was similarly variable, with confidence limited by incomplete protocol reporting, variable assessment of publication bias, and insufficient discussion of heterogeneity.

The takeaway from this ambitious synthesis is a call for both humility and better science. Molecular diagnostics, especially next-generation sequencing, are genuinely promising adjunctive tools that can unmask pathogens in a meaningful share of culture-negative cases, but they do not eliminate false negatives, cannot replace phenotypic susceptibility testing, and must be interpreted in the context of prior antibiotics, specimen type, contamination risk, and the overall clinical picture. The authors argue that the first priority remains optimizing conventional culture: obtaining multiple tissue specimens and synovial fluid before antibiotics are given, using appropriate transport and media, prolonging incubation to at least fourteen days, and employing sonication or blood culture bottles where available. Until rigorous primary studies with standardized definitions and reporting are conducted, culture-negative periprosthetic joint infection will remain what it has long been: a common, consequential, and stubbornly opaque challenge at the intersection of surgery and microbiology.

Subject of Research: Culture-negative periprosthetic joint infection: prevalence, molecular diagnostics, treatment, and evidence limitations

Article Title: Culture-negative periprosthetic joint infection: an umbrella review of prevalence, diagnostic strategies, treatment, and methodological limitations

Article References: Bocchino, G., Maccauro, G., Zampoli, A., Papalia, R., Indelli, P. F., Pérez-Prieto, D., & Parvizi, J. (2026). Culture-negative periprosthetic joint infection: an umbrella review of prevalence, diagnostic strategies, treatment, and methodological limitations. Journal of Bone and Joint Infection, 11(4), 479-488. https://doi.org/10.5194/jbji-11-479-2026

Image Credits: AI Generated

DOI: 10.5194/jbji-11-479-2026

Keywords: periprosthetic joint infection, culture-negative infection, next-generation sequencing, metagenomics, joint arthroplasty, molecular diagnostics, antibiotic stewardship, two-stage exchange, biofilm, sonication, umbrella review, orthopedic surgery

The molecular logic of the new classification rests on a small set of defining alterations. Adult-type diffuse gliomas are now divided into three primary entities. Astrocytoma, IDH-mutant is characterized by mutations in the IDH1 or IDH2 genes, typically accompanied by ATRX and TP53 alterations and the absence of 1p/19q codeletion; its grading incorporates the presence of CDKN2A/B homozygous deletion, which confers a grade 4 designation regardless of histology. Oligodendroglioma requires the dual signature of IDH mutation and whole-arm 1p/19q codeletion. Glioblastoma, IDH-wildtype, the most aggressive form, can be diagnosed in any IDH-wildtype diffuse glioma carrying a TERT promoter mutation, EGFR amplification, or the characteristic +7/−10 cytogenetic pattern, even without classic histological features. Pediatric-type gliomas, driven by histone H3 alterations or MAPK pathway dysregulation, form their own molecularly coherent categories. Each of these definitions depends on tests that go far beyond conventional histopathology.

The major international guidelines have converged on this framework. The WHO CNS5, the National Comprehensive Cancer Network, the European Association of Neuro-Oncology, and the Italian Association of Neuro-Oncology all designate IDH1/2 mutation testing as essential, with 1p/19q codeletion assessment required whenever an IDH-mutant tumor is identified. TERT promoter mutation, EGFR amplification, and +7/−10 status are required to establish a glioblastoma diagnosis under WHO criteria, while MGMT promoter methylation is recommended as a predictive biomarker for temozolomide response. The Italian guidelines go further operationally, defining mandatory core tests, integrated grading that incorporates CDKN2A/B deletion, and structured flowcharts that standardize reporting from tissue handling through molecular testing to final integrated diagnosis. On paper, the global standard is clear and consistent.

The problem is that the technologies needed to meet that standard are unevenly distributed. Immunohistochemistry, the workhorse of pathology, costs roughly €290 per test and can detect IDH1 R132H, ATRX loss, p53 accumulation, and H3 K27M within one to two days in a standard pathology laboratory. Fluorescence in situ hybridization, at approximately €795, visualizes 1p/19q deletion and EGFR amplification with high specificity. PCR-based methods, including quantitative PCR, multiplex ligation-dependent probe amplification, and digital PCR, cost between roughly €261 and €600 and cover an impressive range of essential biomarkers, from whole-arm 1p/19q codeletion to TERT promoter mutations and MGMT methylation. Targeted next-generation sequencing panels, at around €1538, offer broader characterization but demand sequencing platforms, bioinformatics infrastructure, and specialized staff. Genome-wide DNA methylation profiling, costing €2000 to €3000 per test, remains concentrated in a handful of reference centers.

Surveys from the Asian Oceanian Society of Neuropathology paint a sobering picture of who can actually access these tools. Fewer than 15 percent of centers in low- and middle-income countries have access to next-generation sequencing, and methylation profiling is virtually absent. Most institutions in these settings rely on immunohistochemistry and limited PCR-based assays. Even within high-income nations, access is stratified: rural and community hospitals in Europe often lack next-generation sequencing and methylation platforms, while in the United States substantial disparities persist between academic institutions and community hospitals in bioinformatics capacity, reimbursement, and neuropathology expertise. In China, genomic capacity has expanded rapidly in major urban centers, yet the ratio of sequencing-capable facilities to population varies by an order of magnitude between coastal metropolitan areas and inland provinces. Japan and South Korea have achieved broader access through national insurance reimbursement for targeted panels, though regional concentration remains pronounced.

The review is emphatic that this is not simply a story of rich centers versus poor ones. The authors argue that presenting sequencing and methylation arrays as universal gold standards reflects the practice of a minority of well-resourced institutions and does not align with global diagnostic realities. For the majority of glioma patients, a tiered strategy built on immunohistochemistry, PCR-based assays, and multiplex ligation-dependent probe amplification yields all the clinically actionable information needed for diagnosis, grading, and treatment planning. Each technique occupies a distinct niche: multiplex ligation-dependent probe amplification remains particularly useful for whole-arm 1p/19q assessment, while digital PCR offers exceptional sensitivity for low-allele-fraction variants such as TERT promoter mutations. No single modality addresses every diagnostic question, and the appropriate test should be determined by the clinical question, not by the available technology.

The economics of inaction are striking. A single cycle of temozolomide administered to a patient whose glioblastoma lacks MGMT promoter methylation, and who therefore derives minimal benefit, often costs more than the methylation assay itself. Without testing, temozolomide is given empirically to all glioblastoma patients despite limited benefit in roughly 60 percent of unmethylated cases. Patients with 1p/19q-codeleted oligodendroglioma who do not receive procarbazine, lomustine, and vincristine chemotherapy with radiation may lose years of survival compared with those treated according to molecular subtype. Misclassification cascades into ineffective therapies, unnecessary toxicity, accelerated progression, earlier salvage treatment, more emergency admissions, and ultimately greater disability, caregiver burden, and lost productivity. The cumulative societal cost of diagnostic inaccuracy, the review concludes, dwarfs the upfront investment in molecular testing.

The consequences extend beyond individual treatment decisions into the research enterprise itself. Contemporary glioma trials are increasingly molecularly driven, and centers without testing capability cannot screen or enroll eligible patients, producing what the authors call diagnostic deserts and trial deserts, regions where patients are excluded from cutting-edge research not because of clinical ineligibility but because of missing infrastructure. Historical trials conducted without molecular stratification are now difficult to interpret, since treatment benefits are often confined to molecular subgroups. Biobanks lacking molecular annotation have limited value for biomarker discovery. At a global scale, the published molecular landscape of gliomas is heavily biased toward populations served by well-resourced centers, potentially overlooking biological features unique to underrepresented regions.

The barriers to change form a self-reinforcing cycle. High costs and unstable funding restrict the test menu and force dependence on send-out testing with long turnaround times. Shortages of neuropathologists, molecular biologists, and bioinformaticians, worsened by brain drain to high-income countries, lead to errors in test selection and interpretation. Non-standardized tissue fixation and inadequate quality control compromise sample integrity, while bureaucratic delays in approving and reimbursing new tests slow adoption. Limited exposure to the full spectrum of diagnostic modalities then prevents local expertise from developing, perpetuating the cycle from the beginning.

The proposed remedy is a three-tiered framework rather than a demand for universal high-end sequencing. Tier 1, essential and universally accessible, combines histopathology and immunohistochemistry with qPCR, multiplex ligation-dependent probe amplification, or digital PCR for the core biomarkers, delivering actionable results in one to five days with minimal bioinformatics. Tier 2 provides targeted sequencing panels through regional hub laboratories for ambiguous cases and trial candidates. Tier 3 concentrates methylation profiling in reference centers serving large populations. Supporting strategies include hub-and-spoke networks endorsed by the Lancet Commission on Diagnostics, telepathology platforms that allow remote expert interpretation, health technology assessments that explicitly weigh the cost of non-implementation, and workforce initiatives such as the MNP Outreach program, which offers free methylation testing to more than 300 patients annually in Pakistan. The authors also call on the WHO to promote regional reference laboratories, define a minimum diagnostic standard achievable with Tier 1 technologies, and negotiate affordable reagent pricing. The central message is one of pragmatic optimism: an accurate, clinically actionable glioma diagnosis is achievable today for most patients using existing, affordable technologies, provided the political will and organizational frameworks exist to deliver them. The alternative is a consolidated two-tiered neuro-oncology in which access to precision medicine is determined by geography rather than need.

Subject of Research: Global disparities in the implementation of molecular diagnostics for glioma classification under the WHO CNS5 framework

Article Title: The Price of Precision: A Critical Review of Molecular Diagnostics in Glioma, From Guidelines to Global Disparities

Article References: Guarnaccia, M., & Cavallaro, S. (2026). The Price of Precision: A Critical Review of Molecular Diagnostics in Glioma, From Guidelines to Global Disparities. Annals of Clinical and Translational Neurology, 13(10), 1968-1977. https://doi.org/10.1002/acn3.70503

Image Credits: AI Generated

DOI: 10.1002/acn3.70503

Keywords: glioma, molecular diagnostics, WHO CNS5, IDH mutation, 1p/19q codeletion, glioblastoma, health economics, global health disparities, next-generation sequencing, MGMT methylation, neuro-oncology, LMICs

The team, led by Hidehiko Kawai and Hiroyuki Kamiya, set out to dissect the mutational consequences of reactive oxygen species generated under chronic irradiation conditions that mimic low-dose, low-dose-rate exposures. This regime is biologically important because cancers arising after such exposures are largely indistinguishable from spontaneous tumors, making it extremely hard to define the mutational mechanisms at work. Under these conditions, radiation-generated reactive oxygen species are thought to inflict persistent low-level oxidative DNA damage rather than the dramatic double-strand breaks associated with high-dose irradiation. The central challenge has been to connect that diffuse chemical damage to specific, quantifiable mutational outcomes at defined DNA positions, something conventional mutagenesis assays have struggled to achieve with single-molecule resolution.

To overcome this limitation, the researchers employed a next-generation sequencing version of the classical supF shuttle vector assay, enhanced with a random twelve-nucleotide barcode incorporated into each vector molecule. This nucleotide-barcoding strategy is the technical heart of the study. Because every vector molecule carries a unique barcode, each independent mutational event can be identified and counted individually, allowing the team to distinguish true single-molecule mutation events from sequencing artifacts or clonal amplification. The assay was run under both standard supF-selection conditions and without selection, and mutation frequencies and spectra were quantified across the entire supF reporter gene. In parallel, the team prepared shuttle vector libraries carrying a single, site-specific 8-oxo-G lesion at defined positions, providing a controlled benchmark against which the irradiation-induced mutational patterns could be compared.

The results from chronic gamma irradiation were striking. Irradiation significantly increased mutations at C:G base pairs located within 5′-TCN-3′:5′-NGA-3′ sequence contexts, where N denotes any nucleotide. This trinucleotide-level specificity echoes the kind of sequence-context dependence that has become familiar from large-scale cancer genomics, in which different mutational processes leave characteristic footprints in particular sequence neighborhoods. But the more unexpected finding was positional: many of the positions that responded to irradiation were already spontaneous mutation hotspots, and they also coincided with distant C:G sites that were preferentially mutated in response to a single 8-oxo-G lesion placed elsewhere in the vector.

That coincidence points to the study’s most conceptually provocative result, a phenomenon the authors describe as strand-biased action-at-a-distance mutagenesis. When a single 8-oxo-G lesion was introduced at one defined site, mutations did not simply accumulate at or immediately adjacent to the lesion. Instead, the lesion induced extensive mutations at distant C:G sites, and these mutations showed a pronounced strand bias, preferentially affecting one strand of the duplex over the other. Chronic gamma irradiation further enhanced these distant mutations without substantially altering their positional distribution. In other words, irradiation did not create a new and distinct set of mutation sites; it amplified a pre-existing pattern of susceptible positions that was already latent in the molecule.

This amplification model has significant implications for how scientists interpret mutational signatures in cancer genomes. If radiation-induced mutagenesis largely reinforces spontaneous hotspots rather than generating an independent radiation-specific landscape, then the mutational signature of chronic low-dose radiation may be subtle and entangled with background processes, which is consistent with the clinical observation that radiation-associated cancers are so hard to distinguish from spontaneous ones. The finding also suggests that the identity of the damaged base may matter less than the structural and sequence context in which it sits, since a lesion at one position can shape mutational outcomes many bases away.

What could mechanistically explain action-at-a-distance mutagenesis and its strand bias? The authors found important clues in the local secondary structures that single-stranded DNA can adopt. During replication, transcription, or repair, stretches of DNA transiently become single-stranded, and these single-stranded regions are chemically vulnerable and can fold into hairpins and other structures. The study’s hotspot and coldspot behaviors, as well as position-dependent substitution patterns, were associated with predicted local secondary structures of single-stranded DNA. This suggests that structural context contributes to mutagenesis beyond the trinucleotide sequence context alone, adding a layer of physical geometry to the sequence-based models that currently dominate the field of mutational signature analysis.

Strand bias itself is a well-recognized feature of mutational processes in cancer genomics, often reflecting whether a lesion sits on the leading or lagging strand during replication, or on the transcribed versus non-transcribed strand during transcription-coupled repair. The strand-biased mutations observed here, driven by a single oxidative lesion and modulated by chronic irradiation, provide a controlled experimental system in which such biases can be studied mechanistically rather than inferred statistically from tumor sequencing data. The authors note that processes such as translesion DNA synthesis, in which specialized polymerases copy across damaged bases, and base excision repair, in which glycosylases such as OGG1 remove oxidized guanine, are natural candidates for the enzymatic pathways that convert a localized lesion into distant, strand-biased mutations, although the present study defines the patterns rather than fully resolving the responsible mechanisms.

Methodologically, the barcoded supF NGS platform represents a versatile new framework for mutagenesis research. Classical shuttle vector assays, which date back decades, allowed mutated plasmids recovered from cells to be sequenced, but they could not easily distinguish independent events or achieve the throughput needed to map mutation positions comprehensively. The addition of random twelve-nucleotide barcodes and next-generation sequencing changes that calculus, enabling precise quantification of mutation frequencies and spectra at single-molecule resolution. The authors position the platform as a general tool for mechanistic studies of oxidative, radiation-associated, and cancer-related mutagenesis, and it is easy to imagine its application to other lesions, other exposure regimes, and cells deficient in specific repair pathways.

The broader significance of the work lies in reframing how low-dose radiation risk might be understood at the molecular level. Rather than radiation writing a wholly new mutational script into the genome, the study suggests it turns up the volume on a script that oxidative metabolism has already written, preferentially at pre-existing susceptible sites whose locations are governed by sequence context and single-stranded DNA structure. For cancer epidemiology, this offers a potential explanation for why chronic low-dose exposures are so difficult to trace in tumor genomes, and for mutagenesis biology, it elevates DNA secondary structure from a curiosity to a first-class determinant of where mutations strike. As the authors conclude, chronic low-dose-rate gamma irradiation and a single 8-oxo-G lesion promote closely related mutational processes that act preferentially at pre-existing susceptible sites and generate strand-biased action-at-a-distance mutations, a set of strand-bias laws that may ultimately sharpen both radiation risk assessment and the interpretation of mutational signatures across human cancers.

Subject of Research: Strand-biased mutagenesis induced by oxidative DNA damage and chronic low-dose-rate gamma irradiation

Article Title: Systematic mutagenesis assay promotes comprehension of the strand-bias laws for mutations induced by oxidative DNA damage

Article References: Kawai, H., Ebi, S., Sugihara, R., Fujiwara, C., Fujikawa, Y., Kimura, S., & Kamiya, H. (2026). Systematic mutagenesis assay promotes comprehension of the strand-bias laws for mutations induced by oxidative DNA damage. BMC Cancer. https://doi.org/10.1186/s12885-026-17081-0

Image Credits: AI Generated

DOI: 10.1186/s12885-026-17081-0

Keywords: 8-oxo-G, oxidative DNA damage, ionizing radiation, mutagenesis, strand bias, mutation hotspots, supF shuttle vector, next-generation sequencing, reactive oxygen species, DNA secondary structure, cancer, base excision repair

The case began in December 2022, when a 40-year-old male patient presented with symptomatic COVID-19 at the Sonoma County Public Health Laboratory. The patient, who had received a bivalent booster vaccination on October 24, 2022, following earlier doses in 2021, reported symptom onset on December 4, including fever above 38 degrees Celsius, chills, cough, and headache consistent with a mild influenza-like illness. He had been in close contact with a confirmed COVID-19 case and had a prior history of testicular teratoma, but no hospitalization or complications were reported. A nasal specimen collected on December 13, 2022 tested positive for SARS-CoV-2 RNA by an FDA-authorized reverse transcription real-time PCR assay targeting the ORF1ab and nucleocapsid genes, yielding a cycle threshold value of 22, indicative of a substantial viral load in the sample.

To characterize the virus genetically, the laboratory extracted RNA from 300 microliters of the nasal specimen using an automated Chemagic 360 Extractor and prepared a sequencing library with the Clear Dx SARS-CoV-2 Kit from Clear Labs. This automated workflow begins with complementary DNA synthesis from the extracted RNA, followed by multiplex tiling PCR using a panel of barcoded target capture primers to amplify the complete viral genome. After purification with Ampure XP beads to remove excess primers and short amplification products, the amplicons underwent a second round of PCR to incorporate a second set of barcodes using rapid library primers from Oxford Nanopore Technologies. Sequencing adapters were then ligated to the dual-barcoded amplicons, and the finished library was loaded onto a MinION flow cell and sequenced on a GridION instrument for 12 hours.

Bioinformatic processing was carried out with the TheiaCoV_ClearLabs workflow version 2.3.0 on the Terra platform, which employs a reference-based assembly approach using the Wuhan-Hu-1 reference genome. Raw reads were subjected to quality control and adapter trimming, human-derived reads were removed with the NCBI SRA Human Scrubber tool, and the remaining de-hosted reads were aligned to the reference with minimap2. After primer trimming, variant calling and consensus generation were performed with Medaka based on allele frequency thresholds. The sequencing run produced 75,041 raw reads, of which 42,135 were classified as SARS-CoV-2 reads. The resulting consensus genome, designated CA-SCPHL-22-02592, spanned 29,574 nucleotides with 100 percent coding-complete coverage and a mean read depth of 1,112-fold, providing an exceptionally high-quality assembly for downstream analysis.

Lineage assignment placed the virus in Pango lineage BQ.1.1.5 within Nextstrain clade 22E, an Omicron sublineage known to be circulating locally at the time of infection. However, during genome annotation the analysts identified something far less ordinary: a 69-nucleotide in-frame deletion at genomic positions 3272 to 3340 within nsp3 of the ORF1a gene. Because Nanopore sequencing can be prone to insertion-deletion errors, the team rigorously assessed read-level support for the deletion using a custom Python script that parsed CIGAR strings from the alignment file. After quality filtering, 707 of 718 informative reads spanning the deletion breakpoints supported the deletion, corresponding to 98.47 percent read support, with only 11 reads supporting the wild-type sequence. Applying a more stringent filter requiring a mean read quality score of at least 20 yielded consistent results, with 98.30 percent support, providing strong evidence that the deletion is biological rather than an artifact of the sequencing platform.

A search of the GISAID database revealed just how rare this event is. Among 17,624,674 SARS-CoV-2 genomes available at the time, only 23 contained the ORF1a delta-69 deletion at these positions. The earliest sequence carrying the deletion was collected in December 2021 in Brazil and the most recent in March 2023 in the Brazilian Amazon. Strikingly, the deletion appeared across multiple Pango lineages and Nextstrain clades, including both Delta and Omicron variants: four sequences belonged to AY.99.2, one each to BA.1 and BA.1.1, four to BA.2, one to BQ.1, ten to BQ.1.1.5, and two to XBB.1.5.102. This distribution suggests the deletion is not lineage-specific and may arise independently in different viral genetic backgrounds. Notably, nearly all of the BQ.1.1.5 sequences harboring the deletion, with the exception of one from Sweden, were detected in California and exhibited nucleotide sequence identity between 99.96 and 100 percent, hinting at a localized cluster of related viruses.

To place the finding in evolutionary context, the team performed phylogenetic and cluster analysis using the TheiaCoV_Augur_Run workflow, which executes subcommands from the Nextstrain Augur toolkit to generate maximum-likelihood and time-resolved phylogenetic trees visualized in the Auspice web application. The analysis grouped the deletion-containing genomes with representatives of 207 distinct deletion patterns identified within ORF1a positions 3250 to 3350. Broader mining of GISAID identified 2,817 high-coverage sequences carrying deletions of varying lengths in this region, observed across Alpha, Beta, Delta, Epsilon, Iota, Gamma, Kappa, Mu, and Omicron clades as well as recombinant lineages, with the majority belonging to the Delta clade. These deletions of varying lengths within the 3250 to 3350 window had not been previously described in this systematic form, underscoring how a single unusual case can open a window onto a broader landscape of viral genetic diversity.

The functional implications of the deletion remain speculative but are grounded in what is known about nsp3 biology. ORF1a encodes a large polyprotein that is proteolytically processed into multiple non-structural proteins essential for viral replication and host interaction, and nsp3 is the largest and most functionally diverse of these, containing domains involved in proteolytic processing, replication complex organization, and interactions with host factors. The ORF1a delta-69 deletion lies predominantly within the N-terminal hypervariable region of nsp3, with a small portion extending into the ADP-ribose-1-phosphatase domain, also known as the macrodomain or Mac1. This region sits outside the well-characterized catalytic papain-like protease domain and is associated with protein-protein interactions and structural organization. Structural and evolutionary analyses of SARS-CoV-2 proteins indicate that insertions and deletions tend to occur in flexible, surface-exposed regions that tolerate localized sequence variation without disrupting overall protein architecture, consistent with the deletion’s placement in the hypervariable region.

Nevertheless, the partial overlap with the Mac1 domain is noteworthy because this domain counteracts host ADP-ribosylation-mediated antiviral responses, thereby facilitating viral replication and immune evasion. Although the deletion does not encompass the full domain, its partial overlap with a functional region raises the possibility of effects on domain stability or host interaction, and alterations within nsp3 could influence host-virus interactions and contribute to functional differences between SARS-CoV-2 and related coronaviruses such as SARS-CoV. The authors caution that, given the limited functional data available for this specific deletion and its rarity, these potential effects remain speculative. Confirmation using orthogonal approaches such as RT-PCR with flanking primers or Sanger sequencing would further strengthen confidence in the finding, and future studies using reverse genetics systems, protein structural modeling, and in vitro replication assays will be needed to assess any effects on viral replication, host interaction, and immune modulation.

The study also carries practical implications for diagnostics and surveillance. Deletions in viral genomes can affect the performance of molecular assays, particularly those relying on RT-PCR, where primer or probe binding sites could be disrupted, and they are equally relevant for amplicon-based enrichment approaches used prior to sequencing. A limitation of the work is the lack of clinical metadata for the other genomes harboring the ORF1a delta-69 deletion in public databases, which made it impossible to assess whether the deletion is associated with specific clinical outcomes or disease severity. The consensus genome from this case has been deposited in GISAID under accession number EPI_ISL_16171374, and the custom Python code used to quantify read-level deletion support is publicly available on GitHub. As SARS-CoV-2 continues to evolve, the integration of next-generation sequencing into routine surveillance frameworks remains essential for detecting emerging mutations, characterizing their functional consequences, and informing public health response and diagnostic strategies.

Subject of Research: A rare in-frame deletion in the SARS-CoV-2 ORF1a nsp3 gene detected through genomic surveillance

Article Title: Genomic monitoring of SARS-CoV-2 uncovers rare in-frame deletion in ORF1a (nsp3) gene: A case report

Article References: Goraichuk, I. V., Critchett, L., Gonzalez, C., Rubin, J., & Rees, R. (2026). Genomic monitoring of SARS-CoV-2 uncovers rare in-frame deletion in ORF1a (nsp3) gene: A case report. Heliyon, 12(15), Article e45522. https://doi.org/10.1016/j.heliyon.2026.e45522

Image Credits: AI Generated

DOI: 10.1016/j.heliyon.2026.e45522

Keywords: SARS-CoV-2, genomic surveillance, ORF1a, nsp3, in-frame deletion, next-generation sequencing, Oxford Nanopore, GISAID, BQ.1.1.5, Omicron, macrodomain, public health laboratory

The scale of the analysis is one of its distinguishing strengths. The investigators tested 19,523 respiratory specimens from children admitted to the hospital with acute respiratory infections, screening each sample for human adenovirus using targeted next-generation sequencing, a technique that allows simultaneous detection and initial genetic typing of the virus. Overall, 1,704 samples tested positive, corresponding to a detection rate of 8.7 percent. That figure underscores how substantial a burden adenovirus places on pediatric inpatient services in the region, particularly given that the study period spanned three full respiratory seasons following the disruption of the COVID-19 pandemic years.

Demographic patterns in the data were striking and statistically robust. Detection rates were significantly higher in boys than in girls, a difference the authors report with a P value of 0.002, and age proved to be an even stronger determinant of infection risk. Children between three and six years old showed the highest detection rate of any age group, at 11.9 percent, with significant heterogeneity across age strata overall. This preschool peak is consistent with the epidemiology of adenovirus in many settings, reflecting the combination of close contact in kindergartens and playgrounds, immature immune memory, and the high viral shedding that young children can sustain during respiratory illness.

Beyond simply measuring how often the virus appeared, the team went on to determine which genotypes were responsible. From the positive samples, 1,447 could be successfully genotyped, and the analysis revealed 14 distinct genotypes belonging to five of the seven human adenovirus species, designated A, B, C, E, and F. Two types towered over the rest: HAdV-3 accounted for 51.5 percent of genotyped infections and HAdV-7 for 18.4 percent, followed by HAdV-1 at 12.2 percent, HAdV-2 at 6.6 percent, HAdV-21 at 6.3 percent, HAdV-5 at 2.4 percent, and HAdV-4 at 1.3 percent, with remaining genotypes making up the final 1.3 percent. To confirm the sequencing-based typing, the researchers randomly selected positive samples for conventional PCR amplification of the hexon gene, the principal surface protein-coding region used in adenovirus classification, and performed phylogenetic analysis against reference sequences from GenBank.

Perhaps the most consequential finding is that genotype composition changed systematically with the age of the host. Preschool and school-aged children were infected mainly with HAdV-3 and HAdV-7, both members of species B, whereas infants and toddlers were predominantly infected with HAdV-3 and HAdV-1, the latter belonging to species C. The association between age group and genotype was highly significant, with a P value below 0.001. This age-stratified structure has practical implications: it suggests that the viruses circulating in daycare and school environments differ from those afflicting children in their first years of life, and that any vaccination or prevention strategy may need to account for these distinct transmission niches.

Seasonality added another layer of structure to the epidemiology. Adenovirus was detected year-round, but the detection rate varied markedly by season, peaking in winter at 13.4 percent of tested specimens. The seasonal pattern intersected with genotype in an unexpected way. Species B viruses, particularly HAdV-3 and HAdV-7, dominated the winter months, while species C viruses, especially HAdV-1, were more commonly identified in summer. This genotype-season coupling, significant at P below 0.001, implies that winter respiratory disease admissions driven by adenovirus are not simply more frequent but also caused by a different set of viral types than summer cases, a nuance that could inform the timing of clinical preparedness and laboratory typing efforts.

Temporal analysis across the three study years revealed an inter-annual shift in the viral population that may prove to be the study’s most cited observation. Before August 2023, species C adenoviruses were the predominant circulating group; after that point, species B took over as the dominant species. Such species-level turnover in a community setting is rarely documented with this level of resolution, and it raises questions about what ecological forces, whether waning population immunity, changes in contact patterns, or intrinsic viral fitness differences, drove the replacement. The authors’ data cannot answer that question definitively, but the documented shift provides a benchmark against which future surveillance in Tianjin and comparable regions can be measured.

The clinical correlations are equally important for pediatric practice. The main diagnoses among adenovirus-positive children included pneumonia, bronchitis, tonsillopharyngitis, and upper respiratory tract infections. Genotype-phenotype association analysis showed that HAdV-3 and HAdV-7 were the predominant types in pneumonia cases, whereas HAdV-3 and HAdV-1 were more commonly associated with tonsillopharyngitis and upper respiratory tract infections. Most critically, children infected with HAdV-7 were significantly more likely to develop severe pneumonia, an association with a P value below 0.001. This finding aligns with the established reputation of HAdV-7 as the most virulent of the common respiratory adenovirus types and highlights why molecular typing of adenovirus in hospitalized children is not merely an academic exercise but can carry direct prognostic value at the bedside.

For the study’s authors, the combined epidemiological, seasonal, and clinical picture supports a case for region-specific surveillance and targeted interventions. Because HAdV-3, HAdV-7, and HAdV-1 together accounted for the overwhelming majority of typed infections, they represent the logical priority targets for any multivalent vaccine formulated for this population. No licensed adenovirus vaccine is currently available for routine pediatric use in most countries, and existing military vaccines cover only types 4 and 7. The genotype distribution documented in Tianjin, with its clear dominance of type 3 and its age-specific and seasonal structure, offers exactly the kind of empirical evidence that vaccine developers and public health planners need when weighing which valences to include and how to prioritize rollout.

The study also demonstrates the value of combining modern sequencing platforms with classical molecular methods. Targeted next-generation sequencing enabled high-throughput screening and typing across nearly twenty thousand specimens, while hexon gene PCR and phylogenetic analysis provided confirmatory genotyping anchored to international reference databases. The retrospective design, approved by the Ethics Committee of Tianjin Children’s Hospital with a waiver of written informed consent because de-identified residual specimens were used, allowed the team to assemble a dataset of unusual breadth without additional burden on patients. As respiratory virus surveillance becomes increasingly genomic in the post-pandemic era, this work illustrates how sustained, genotype-resolved monitoring of a single pathogen in a single pediatric population can reveal patterns, from species turnover to genotype-specific severity, that would be invisible to conventional diagnostic testing alone, and it establishes a detailed baseline for tracking how adenovirus evolution continues to shape childhood pneumonia in northern China.

Subject of Research: Molecular epidemiology and clinical characteristics of human adenovirus in hospitalized children with respiratory infections in Tianjin, China

Article Title: A comprehensive analysis of molecular epidemiology and clinical characteristics of human adenovirus among hospitalized children with pneumonia in Tianjin, China, 2022–2025

Article References: Fang, Y., Dong, L., Hou, M., Lei, M., Guan, X., & Cai, C. (2026). A comprehensive analysis of molecular epidemiology and clinical characteristics of human adenovirus among hospitalized children with pneumonia in Tianjin, China, 2022–2025. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14452-7

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14452-7

Keywords: human adenovirus, pediatric pneumonia, acute respiratory infection, HAdV-3, HAdV-7, genotype surveillance, next-generation sequencing, hexon gene, seasonality, vaccine development, Tianjin, BMC Infectious Diseases

The study, published in BMC Genomics by Aitor Almanza of Navarrabiomed and colleagues, addresses a gap that has widened as genomic medicine has scaled up. Next-generation sequencing has transformed precision medicine, but the analytical workflows behind it have become increasingly complex, involving multiple extraction steps, library preparations, batching events and platform transfers. Each handoff is an opportunity for error. While the frequency of sample misidentification may be low, the researchers note that the potential negative outcomes are worrying, particularly in clinical contexts where a wrong sample match can influence diagnosis or treatment decisions. Existing SNP-based quality control solutions, they argue, tend to rely on non-coding genetic markers or require advanced technologies that many laboratories do not have, leaving a need for small, robust panels that are portable across technologies, compatible with diagnostic panels, applicable across diverse populations and straightforward to implement in a wet lab.

The core idea behind the new panel is elegantly simple. Every person carries millions of genetic variants, and the specific combination of variants at a carefully chosen set of positions acts like a molecular fingerprint that is essentially unique to an individual. If a laboratory genotypes those positions in a sample at the start of a workflow and again at the end, or compares a sequencing result against a reference profile collected earlier, any mismatch immediately flags a possible sample swap or contamination. The challenge lies in choosing which variants to include. The markers must be highly discriminant, meaning that the chance of two unrelated people sharing the same profile is vanishingly small. They must also be compatible across platforms, so that a profile generated on a sequencer can be compared with one generated on a qPCR machine, and they must work reliably in populations around the world rather than being calibrated to a single ancestry group.

To build the panel, the team applied a stringent filtering pipeline designed to identify highly discriminant, cross-platform compatible genetic markers supported by predesigned TaqMan assays. TaqMan assays are a widely used qPCR genotyping chemistry in which fluorescent probes report which allele is present at a specific position, making the technology a staple of clinical molecular laboratories. By restricting the candidate markers to SNPs that already have validated, commercially available TaqMan assays, the researchers ensured that any laboratory with standard qPCR infrastructure could adopt the barcode without developing new reagents from scratch. They also prioritized SNPs that are already present in clinical sequencing panels, a decision with important practical consequences: it means the barcode can often be read directly from data that clinical laboratories are already generating, without any additional sequencing effort.

Population applicability was a central design criterion. A barcode that discriminates well in European populations but poorly in East Asian or African populations would be of limited use in the diverse patient cohorts of modern medicine. The researchers therefore prioritized markers with broad applicability across world populations, drawing on allele frequency data to ensure that the panel retains its discriminatory power regardless of the ancestry of the person being tested. This focus distinguishes the panel from earlier identity-testing approaches that were often optimized for specific populations or that relied on markers whose behavior across ancestries was less well characterized. The result is a barcode intended to be genuinely portable, both technologically and demographically.

The validation of the panel drew on the NAGENDATA cohort, a collection of neuropathology samples from Navarra, Spain, gathered under informed consent for research use and approved by the Research Ethics Committee of Navarra. The team used whole-genome sequencing data from 150 samples in the cohort to establish reference profiles and then cross-validated the barcode with qPCR genotyping. The numbers reported are striking. The full 44-SNP panel demonstrates exceptional discriminatory power, with theoretical cumulative random match probabilities ranging from 2.43 times ten to the power of minus nineteen in European populations to 9.37 times ten to the power of minus eighteen in East Asian populations. In plain terms, the probability that two unrelated individuals share the same 44-SNP profile is so small, on the order of one in many quintillions, that a matching profile can be treated as conclusive evidence of identity for practical purposes.

Cross-platform performance is where the panel earns its clinical credentials. When the researchers compared profiles generated by next-generation sequencing with those generated by qPCR, they found 99 percent concordance between the two technologies. That level of agreement matters because the whole point of a portable barcode is that a profile generated in one laboratory, on one instrument, can be trusted when compared against a profile generated elsewhere, on a different instrument, perhaps years later. A barcode that produced different answers depending on the platform would generate false alarms and erode confidence. The high concordance indicates that the selected SNPs genotype cleanly and consistently across chemistries, a property that reflects careful marker selection as much as analytical rigor.

The panel did not merely perform well in theory; it caught real errors. Combined within-platform and cross-platform analyses successfully identified three cases of sample mislabelling in the NAGENDATA collection. Those three detections, in a cohort of 150 samples, illustrate the kind of silent failures that can lurk in even well-managed biobanks and sequencing facilities. Without an independent genetic check, such mislabelled samples would have propagated through downstream analyses, potentially associating genomic data with the wrong individual and contaminating scientific conclusions. In a clinical workflow, the same failure could have far more serious consequences. The demonstration that a compact barcode can surface these errors retroactively, using data already on hand, underscores the practical value of the approach.

The researchers describe the result as a robust, ready-to-deploy SNP barcode that bridges next-generation sequencing and wet-lab workflows, enabling retrospective sample authentication across sequencing platforms and qPCR systems. The retrospective dimension deserves emphasis. Because many clinical sequencing panels already include the barcode SNPs, laboratories can often authenticate historical samples by extracting the relevant positions from existing sequencing files and comparing them against qPCR profiles or against other sequencing data. This opens the door to auditing past datasets for sample integrity issues without re-extracting DNA or re-running expensive assays, a capability that could be valuable for quality assurance programs, biobank certification and the growing movement toward reproducibility in genomics.

The design choices also reflect the regulatory and economic realities of clinical genomics. Sample tracking and data integrity sit at the intersection of privacy frameworks such as the GDPR and HIPAA, and laboratories need solutions that protect patient identity while verifying it. A 44-SNP barcode is deliberately minimal: it contains far too little information to reconstruct a person’s appearance, health risks or ancestry in any meaningful detail, yet more than enough to distinguish one individual from another. Combined with cost-effective implementation on equipment that most molecular laboratories already own, the panel lowers the barrier to routine sample authentication. As sequencing becomes ever more embedded in research and clinical routine, tools like this barcode point toward a future where every genomic dataset carries an internal, verifiable proof of its own provenance, quietly guarding against the swapped tubes and mislabelled plates that no laboratory is immune to.

Subject of Research: A TaqMan-compatible 44-SNP panel for cross-platform genetic sample authentication and tracking

Article Title: A TaqMan-compatible 44-SNP barcode for robust sample tracking in research and clinical settings

Article References: A TaqMan-compatible 44-SNP barcode for robust sample tracking in research and clinical settings. (n.d.). https://doi.org/10.1186/s12864-026-13282-w

Image Credits: AI Generated

DOI: 10.1186/s12864-026-13282-w

Keywords: sample tracking, SNP barcode, TaqMan, genomics, next-generation sequencing, qPCR, whole-genome sequencing, biobank, data integrity, precision medicine, sample mislabelling, genotyping

The research, conducted at Mayo Clinic in Rochester, Minnesota, describes the institution’s early experience deploying a research-based cerebrospinal fluid (CSF) cell-free DNA profiling program across its neurology, oncology, and neurosurgery departments. Beginning in August 2021 and continuing through December 2024, any clinician performing a clinically indicated lumbar puncture could request that the fluid be analyzed for tumor-derived genetic material. Seventy-six consecutive patients were enrolled under an institutional review board-approved protocol, with informed consent obtained for the brain tumor biomarkers study and for storage in the Mayo Clinic Neuro-Oncology biorepository. The result is a portrait of liquid biopsy testing as it actually happens in a busy hospital — messy, heterogeneous, and full of both promise and practical constraints.

The technical pipeline behind the study is worth understanding, because it illustrates the engineering challenge of detecting vanishingly small amounts of tumor DNA. After collection, CSF samples were kept on ice and centrifuged within one to two hours, then frozen and shipped to Predicine, Inc., where cell-free DNA was extracted using a silica-membrane kit and quantified with a fluorometer and fragment analyzer. The median yield was just 0.27 nanograms per milliliter — a tiny quantity compared with what is typically recovered from blood plasma. Depending on the amount and quality of DNA recovered, samples then underwent either targeted next-generation sequencing of a 152-gene cancer panel on an Illumina NovaSeq 6000, low-pass whole-genome sequencing to generate genome-wide copy-number profiles, or both. Error suppression was achieved by merging sequencing reads from the same DNA molecules into consensus sequences, and a variant was only called as positive if it was supported by at least three independent DNA fragments, including at least one duplex fragment, and met a stringent log-odds threshold.

Patients fell into three broad clinical categories, each representing a classic diagnostic dilemma in neuro-oncology. Forty-six percent had a brain lesion of unknown origin seen on MRI that had not yet been biopsied. Twenty-one percent had a known glioma or other tumor, and their clinicians were trying to distinguish true tumor progression from treatment-related changes such as radiation necrosis or pseudoprogression — a distinction that conventional MRI handles poorly, with sensitivity and specificity ranging from only 30 to 70 percent. The remaining 26 percent had known systemic cancer with new neurological findings, and the question was whether leptomeningeal disease — the spread of cancer into the membranes lining the brain and spinal cord — was present. Cytology, the traditional test for that condition, is notoriously insensitive: in this cohort it was negative in 16 of the 18 patients in whom it was obtained.

Across all three indications, the assay produced what the researchers call a positive tumor call — detection of a cancer-associated variant allele or copy-number alteration — in 20 of the 76 patients, or 26 percent. Another 29 patients, 38 percent, had adequate DNA but no detectable tumor signal, while 27 patients, 36 percent, had insufficient cfDNA yield or quality to permit analysis. Notably, the distribution of positive, negative, and uninformative results was remarkably similar across the three clinical questions, suggesting that the assay behaves consistently regardless of why it is ordered. Only two of the sequencing runs failed quality control, a low failure rate that the authors attribute to careful sample handling and the robustness of the extraction workflow.

One of the study’s most striking findings concerns what predicts success. Increasing the volume of CSF collected did not correlate with the amount of DNA recovered — a counterintuitive result that underscores how heterogeneous tumor DNA shedding is among patients. Instead, positive tumor calls were strongly associated with higher cfDNA concentration itself: samples with detectable tumor signals had a median yield of 0.91 nanograms per milliliter, compared with 0.30 for negative samples and essentially zero for the low-yield group. Tumor proximity to the CSF space is thought to be a major driver of this variability, since fully embedded parenchymal lesions with little contact with CSF are unlikely to release detectable DNA into the fluid. This means that a negative result must always be interpreted in light of the lesion’s anatomy, not as definitive proof of absence of disease.

When tumor DNA was detected, it told clinically meaningful stories. Low-pass whole-genome sequencing uncovered the 1p/19q co-deletion characteristic of oligodendroglioma in one patient and the chromosome 7 gain and chromosome 10 loss typical of glioblastoma in others. Targeted sequencing revealed mutations in genes including TP53, TERT, IDH1, BRAF, EGFR, and MYD88 — the latter a disease-defining alteration in primary central nervous system lymphoma. In the three patients who had also undergone clinical tissue sequencing, CSF and tissue shared a substantial fraction of mutations, but each patient also carried mutations found only in the spinal fluid, a phenomenon the authors attribute to spatial heterogeneity within tumors or to genomic evolution between the times of tissue and fluid sampling.

The study also identified a quantitative biomarker with prognostic power. By summing genome-wide copy-number deviations into a single copy-number burden score, the team found that a threshold of 7.42 cleanly separated samples with true tumor-specific copy-number alterations from those without, achieving an area under the receiver operating curve of 0.998. Patients whose CSF exceeded that threshold had significantly worse overall survival, with a hazard ratio of 3.4 after controlling for the clinical indication. More broadly, patients with any positive tumor call survived significantly less long than those with negative calls or low DNA yield — a difference driven largely by the unknown-diagnosis group, with a similar trend among patients being evaluated for leptomeningeal disease. In other words, even a negative result carries information: abundant tumor DNA in spinal fluid is a bad sign, while its absence, in the right clinical context, is reassuring.

Three case vignettes bring the statistics to life. A 72-year-old man with chronic lymphocytic leukemia presented with confusion and diffuse brain abnormalities on MRI; his CSF revealed chromosome 12 amplification consistent with trisomy 12 CLL, plus KRAS and BRAF mutations, helping confirm rare central nervous system involvement of his leukemia. A 38-year-old man with metastatic gastroesophageal adenocarcinoma showed an extensive copy-number burden and TP53, NTRK1, and EGFR mutations in his spinal fluid, confirming leptomeningeal spread and guiding treatment decisions. And a 51-year-old woman with a surveillance question about her grade 3 oligodendroglioma had her tumor’s molecular signature — the 1p/19q co-deletion and IDH1 R132H mutation — detected in CSF months before imaging confirmed ventricular progression, ultimately informing her enrollment in an IDH inhibitor trial.

The authors are candid about the limitations. The copy-number burden threshold was derived post hoc without an independent validation cohort, tissue sequencing was available for only a handful of patients, and cytology’s poor sensitivity made it an imperfect gold standard for leptomeningeal disease. For progression-versus-pseudoprogression questions, the mixture of recurrent tumor and treatment effects likely explains why survival did not differ by tumor-call status in that subgroup. Still, the study demonstrates that CSF cfDNA sequencing can be deployed across the full breadth of a real neuro-oncology practice with acceptable failure rates, and that requests for testing have grown substantially since the program began. As low-input sequencing platforms mature, the authors argue, spinal fluid liquid biopsy is poised to become a routine complement — and in some cases a safer alternative — to the neurosurgeon’s needle.

Subject of Research: Cerebrospinal fluid cell-free DNA sequencing as a liquid biopsy for diagnosing and monitoring brain tumors and leptomeningeal disease in neuro-oncology practice

Article Title: Early experience with cerebrospinal fluid cell-free DNA molecular profiling in a neuro-oncology practice

Article References: Riviere-Cazaux, C., Kumar, R., Rechberger, J. S., Obiri-Yeboah, D., Dai, C., Li, J., Huang, Y., Warrington, A. E., Sharif, E. H., Palmer, E. A., Wang, X., Lachance, D. H., Kizilbash, S. H., Ruff, M. W., Carabenciov, I. D., Fortin Ensign, S. P., Zadeh, G., Neth, B. J., Sener, U., … Burns, T. C. (2026). Early experience with cerebrospinal fluid cell-free DNA molecular profiling in a neuro-oncology practice. Journal of Neuro-Oncology, 180(1), Article 2. https://doi.org/10.1007/s11060-026-05799-7

Image Credits: AI Generated

DOI: 10.1007/s11060-026-05799-7

Keywords: cerebrospinal fluid, cell-free DNA, liquid biopsy, neuro-oncology, brain tumors, glioma, leptomeningeal disease, next-generation sequencing, copy-number alterations, pseudoprogression, Mayo Clinic, biomarkers

The central question was deceptively simple: does the amount of tumor DNA floating in a patient’s plasma actually mirror what radiologists see on a scan? The answer, according to the analysis led by Isabel Heidrich, with Klaus Pantel and Christoffer Gebhardt as senior authors, is a qualified yes. Circulating tumor DNA levels rose and fell in broad agreement with disease status, increasing significantly as radiologic response worsened across the standard RECIST 1.1 categories, from complete remission through partial remission and stable disease to progression. The statistical association was modest but real, with a Spearman correlation coefficient of 0.31 and a p-value of 0.002 across 99 paired time points.

Yet the study’s most valuable contribution may be its honest accounting of where that agreement breaks down. When the researchers tested how well a single ctDNA measurement could identify progressive disease, the discriminative performance was only moderate, yielding an area under the receiver operating characteristic curve of 0.69. Threshold analyses exposed a fundamental trade-off that clinicians will recognize immediately. Setting the bar high, at 25 or more mutant molecules per milliliter of plasma, produced strong specificity of at least 83 percent but sensitivity of no more than 30 percent, meaning the test rarely cried wolf but also missed most progressing patients. Lower thresholds of one to two mutant molecules per milliliter hovered around 56 percent for both sensitivity and specificity, a level of accuracy that cannot stand alone.

To move beyond categorical imaging readouts, the team also compared ctDNA concentrations directly with total metastatic tumor volume, calculated quantitatively rather than judged by eye. Here the correlation was stronger: ctDNA levels tracked tumor volume with a Spearman coefficient of 0.46, highly significant at p less than 0.0001 across 73 paired time points. Crucially, timing mattered. When blood draws and imaging occurred within 30 days of each other, the correlation tightened to 0.56, while measurements separated by longer intervals showed weaker agreement. This temporal effect carries a practical lesson for clinical trials and routine care alike: a ctDNA result is most informative about tumor burden when it is anchored closely in time to an imaging reference point.

Perhaps the most striking finding, however, concerned change itself. If ctDNA is a faithful liquid biopsy of tumor dynamics, then a rise or fall in plasma DNA should parallel a corresponding change in tumor volume. It did not. Dynamic changes in ctDNA were not significantly correlated with changes in tumor volume, with a correlation coefficient of just 0.20 and a p-value of 0.25. In other words, a patient whose ctDNA dropped sharply was not reliably the patient whose tumors shrank the most. This decoupling of trajectories suggests that ctDNA shedding is governed by biology that a ruler on a scan cannot see, including cell death rates, vascularization, and the metabolic state of individual metastases.

That spatial dimension emerged forcefully from the organ-specific analyses. The strength of the association between ctDNA and tumor burden varied dramatically depending on where the metastases were located. Lymph node and peritoneal metastases showed comparatively strong relationships between ctDNA levels and disease status, while lung, liver, and brain metastases contributed far less detectable DNA to the bloodstream. This pattern of differential shedding has direct clinical implications: a patient whose disease is confined to visceral sites may have undetectable ctDNA despite substantial tumor burden, while another with bulky nodal disease may show abundant plasma DNA. A negative blood test, the study suggests, cannot be interpreted without knowing the anatomy of the disease it is meant to represent.

The researchers also quantified how often ctDNA dynamics and radiologic assessments actually agreed. Concordance was high among patients whose disease was clearly responding, reaching 85 percent in those with complete or partial remission. In stable or progressive disease, agreement fell to 72.9 percent. The discordant cases, rather than being dismissed as noise, were examined descriptively and linked to three plausible culprits: tumor heterogeneity within and across metastatic sites, differences in the timing between blood draws and scans, and treatment-related factors that may alter shedding independently of tumor cell numbers. Immune checkpoint inhibitors, which unleash immune cells to attack tumors, may cause inflammatory swelling or delayed shrinkage that complicates both imaging and biomarker readouts in the early weeks of therapy.

Technically, the study relied on a UMI-based amplicon next-generation sequencing assay capable of detecting mutations in BRAF, EGFR, KRAS, NRAS, and PIK3CA. Unique molecular identifiers allow the sequencing platform to distinguish true mutant fragments from errors introduced during amplification, a critical safeguard when hunting for a handful of mutant molecules in a sea of healthy cell-free DNA. By quantifying ctDNA as mutant molecules per milliliter rather than as a binary positive-or-negative call, the assay enabled the continuous, high-frequency sampling that made the temporal analyses possible. The retrospective design and the modest cohort size of 42 patients mean the findings should be validated prospectively, but the density of sampling, 241 time points, gives the conclusions a robustness that sparse datasets cannot match.

What emerges from the combined analysis is neither a triumph for liquid biopsy nor a rebuttal of it, but a map of its boundaries. ctDNA clearly reflects radiologic disease status and overall tumor burden, and its correlation with volume strengthens when measurements are temporally aligned. At the same time, the moderate discrimination of progression, the weak link between ctDNA dynamics and volume changes, and the pronounced heterogeneity of shedding across metastatic sites all argue against replacing scans with blood tests. Instead, the authors position ctDNA as a complementary biomarker, one that adds a molecular, real-time layer to the anatomical snapshot provided by CT and MRI. For a disease like advanced melanoma, where immunotherapy can produce deep and durable responses in some lesions while others escape, that layered view may be exactly what clinicians need to catch relapse earlier and tailor treatment with greater confidence.

Subject of Research: Longitudinal ctDNA monitoring and its relationship to radiologic response and tumor volume in advanced melanoma

Article Title: Integrated longitudinal analysis of ctDNA, radiologic response, and tumor volume reveals spatial and temporal heterogeneity in advanced melanoma

Article References: Heidrich, I., Streckenbach, A., Rautmann, C., Freiberg, H., Kött, J., Geidel, G., Rünger, A., Zell, T., Roeper, C., Hansen-Abeck, I., Abeck, F., Schneider, S. W., Smit, D. J., Pantel, K., & Gebhardt, C. (2026). Integrated longitudinal analysis of ctDNA, radiologic response, and tumor volume reveals spatial and temporal heterogeneity in advanced melanoma. Journal of Translational Medicine, 24(1), Article 1199. https://doi.org/10.1186/s12967-026-08899-0

Image Credits: AI Generated

DOI: 10.1186/s12967-026-08899-0

Keywords: ctDNA, liquid biopsy, advanced melanoma, immune checkpoint inhibitors, tumor volume, RECIST, tumor heterogeneity, next-generation sequencing, radiologic response, longitudinal monitoring, metastasis, biomarker

The urgency behind the effort is easy to grasp. Intrahepatic cholangiocarcinoma accounts for roughly 8 to 15 percent of all primary malignant liver tumors, second only to hepatocellular carcinoma, and its incidence has been climbing. Five-year overall survival sits at approximately nine percent. Surgery remains the only curative option, yet 70 to 80 percent of patients arrive at the clinic with disease that is either locally unresectable or already metastatic. For them, systemic therapy can delay progression but typically extends survival to only about a year. Against that grim backdrop, the discovery that roughly 40 to 50 percent of these tumors carry actionable genetic alterations has transformed the conversation, turning molecular profiling from an academic exercise into a clinical necessity.

The guideline, developed under the auspices of the Chinese Anti-Cancer Association’s liver cancer and pathology societies with international co-authors from Singapore, Australia, the United States and China, was registered on a transparency platform for practice guidelines and graded its evidence using the GRADE system. Its central message is blunt: molecular testing is recommended for all patients with intrahepatic cholangiocarcinoma, and it is essential for those with unresectable or metastatic disease, because the tumor’s genetic landscape differs markedly from that of extrahepatic bile duct cancers and gallbladder cancers, and even different pathological subtypes of the tumor behave differently at the DNA level.

At the top of the target list sits FGFR2, a receptor tyrosine kinase gene that is rearranged or fused in between 6.6 and 20 percent of Chinese patients with the disease, particularly in the small-duct subtype. These fusions typically break the gene between exons 17 and 19, leaving the receptor’s kinase domain intact while deleting regulatory elements that normally switch the receptor off, resulting in constitutive growth signaling. More than 140 partner genes have been identified, with BICC1 the most frequent. Two drugs, pemigatinib and futibatinib, are now approved by regulators in the United States and China for previously treated patients whose tumors harbor FGFR2 fusions, and both are recommended as second-line options in major treatment guidelines.

Choosing the right detection method for FGFR2 turns out to matter enormously, and the consensus devotes unusual technical detail to the question. Fluorescence in situ hybridization with break-apart probes can flag rearrangements but cannot identify fusion partners and may miss closely spaced intrachromosomal events. DNA-based next-generation sequencing can simultaneously detect mutations, amplifications and fusions across many genes, but it cannot confirm that a detected fusion actually produces a functional RNA transcript. RNA-based sequencing, by contrast, provides direct evidence of functional fusions and can uncover novel partners, with concordance between the two sequencing approaches reaching 98 percent. The panel therefore recommends combining DNA- and RNA-based sequencing, reserving FISH as a fallback when sequencing is unavailable, and explicitly discourages FGFR2 immunohistochemistry, which shows poor agreement with molecular methods. In a striking practical touch, the guideline even borrows interpretation thresholds from ALK testing in lung cancer, since no standardized cutoff for FGFR2 break-apart positivity exists.

A second pillar of the guideline concerns IDH1, a metabolic enzyme whose mutations occur in 4.9 to 20 percent of Chinese patients, again concentrated in the small-duct subtype. The inhibitor ivosidenib received United States approval in 2021 for previously treated, IDH1-mutant cholangiocarcinoma, with a companion diagnostic test cleared alongside it. Mutations cluster at position 132, most commonly R132C, a detail with real diagnostic consequences: the commercial immunohistochemistry antibody targets the R132H variant common in gliomas and cannot recognize R132C, limiting staining’s usefulness here. Sequencing, preferably by next-generation platforms that can capture multiple loci, is the preferred route, and the panel notes that secondary resistance mutations such as D279N, or oncogenic IDH2 mutations like R172K, can emerge under treatment pressure, making comprehensive sequencing valuable even after therapy begins.

The guideline then marches through a roster of additional targets. BRAF V600E, present in a subset of the 4.2 percent of Chinese patients with BRAF mutations, is sensitive to the approved dabrafenib-plus-trametinib combination, while non-V600 variants respond to MEK inhibitors but not BRAF inhibitors, so the panel urges attention beyond the flagship site. HER2 overexpression and ERBB2 amplification, found in 1.8 to 8 percent of patients, open doors to trastuzumab-based regimens including trastuzumab deruxtecan, with immunohistochemistry prioritized and equivocal cases confirmed by FISH or sequencing, interpreted for now by adapting breast and gastric cancer criteria. Rarer but druggable alterations receive their due as well: NTRK fusions in under one percent of patients, RET fusions in 1.8 percent, KRAS mutations in 12.4 to 25 percent, and NRG1 fusions in roughly two percent, each with preferred platforms, mostly RNA-based sequencing for fusions and broad DNA panels for point mutations.

Immune checkpoint eligibility also earns a formal recommendation. Deficient mismatch repair or high microsatellite instability, present in 1.6 to 6 percent of Chinese patients, predicts response to immunotherapy, and several checkpoint inhibitors are approved for such tumors in both the United States and China. The panel endorses mismatch repair immunohistochemistry or polymerase chain reaction-based microsatellite testing as primary methods, and adds a cautionary note drawn from a study of 1,942 solid tumors: sequencing-based microsatellite calls are fully concordant with conventional methods only at the extremes, so borderline results must be validated by immunohistochemistry or PCR before treatment decisions rest on them.

Equally pragmatic are the recommendations about samples themselves. Because intrahepatic cholangiocarcinoma is stroma-rich, tumor cell content in biopsies is often low; in one series of 123 advanced biliary tract cancers, more than a quarter of samples were unsuitable for sequencing due to insufficient tumor content. The consensus requires pathologists to verify at least 20 percent tumor cellularity and a minimum of 50 tumor cells before testing, and urges clinicians to obtain enough tissue in a single procedure for both diagnosis and molecular workup. Tissue remains the gold standard, with cytology cell blocks as the fallback and liquid biopsy of circulating tumor DNA as a last resort at accredited laboratories, since concordance between blood and tissue varies dramatically, from 87 to 100 percent for point mutations down to just 18 percent for FGFR2 fusions. Primary lesions are preferred for initial testing, though metastatic sites may be sampled when the primary is inaccessible, and repeat biopsy after progression on targeted therapy is explicitly encouraged to map resistance mechanisms.

The panel closes by sorting biomarkers into essential and optional categories, the latter including emerging targets such as PTEN loss, Claudin 18.2 expression and BRCA1/2 mutations that may guide trial enrollment, and it commits to periodic revisions as new drugs and data accumulate. For a cancer with a nine percent five-year survival rate, the stakes of getting testing right could hardly be higher. What this guideline offers is a shared playbook: a single, evidence-graded document telling laboratories and clinicians worldwide which genes to interrogate, which platforms to trust, how to interpret ambiguous signals, and when to re-biopsy, so that every patient with this aggressive tumor has the best possible chance of finding a therapy matched to the specific molecular engine driving their disease.

Subject of Research: Precision molecular biomarker testing guidelines for intrahepatic cholangiocarcinoma

Article Title: Guideline of precisional testing in intrahepatic cholangiocarcinoma: an international expert consensus

Article References: Zhang, X., Han, J., Shi, R., Yu, B., Zhang, X., Li, B., Sheng, X., Li, Z., Zou, Y., Sun, H., Shi, G., Wang, H. L., Zhou, J., Fan, J., Cong, W., & Ji, Y. (2025). Guideline of precisional testing in intrahepatic cholangiocarcinoma: an international expert consensus. Clinical Cancer Bulletin, 4(1), Article 9. https://doi.org/10.1007/s44272-025-00036-0

Image Credits: AI Generated

DOI: 10.1007/s44272-025-00036-0

Keywords: intrahepatic cholangiocarcinoma, molecular testing, FGFR2 fusions, IDH1 mutations, next-generation sequencing, targeted therapy, biomarkers, precision oncology, bile duct cancer, HER2, microsatellite instability, expert consensus

The argument builds on a striking real-world study that has recently energized the field. A retrospective, two-stage cohort analysis by Chen and colleagues examined early bone-marrow-guided venetoclax management in patients with newly diagnosed acute myeloid leukemia who were considered unsuitable for intensive chemotherapy. Among 371 evaluable patients, the investigators found that using early marrow assessments to guide treatment was associated with significantly reduced early venetoclax exposure and a marked drop in day-56 infection-related hospitalization, which fell from 37.4 percent to 24.0 percent, corresponding to an adjusted odds ratio of 0.46 with a p-value of 0.005. In other words, simply looking at the marrow earlier allowed clinicians to pull back on the drug before the most dangerous toxicities took hold.

The second stage of the Chen study sharpened the finding further. Among 237 patients who responded to initial therapy, shortening venetoclax to fourteen days or fewer per cycle reduced prolonged grade-4 neutropenia from 61.0 percent to 41.6 percent, an adjusted odds ratio of 0.41 with a p-value of 0.003. Infection-related hospitalization also fell, with an adjusted odds ratio of 0.43 and a p-value of 0.014. Critically, these toxicity reductions came without any significant change in measurable residual disease negativity, overall survival, or relapse-free survival. For a drug whose most feared side effect is profound, prolonged neutropenia that opens the door to life-threatening infections, the implication is provocative: some patients may be receiving more venetoclax than they need, and the excess exposure may be pure harm.

Yet the editorial is careful to frame these results as a beginning rather than an endpoint. Because the Chen study was retrospective, its findings are vulnerable to selection bias; clinicians may have shortened therapy preferentially in patients who already looked healthier, which could inflate the apparent safety benefit. The absence of randomization means the two compared groups may have differed in ways the statistical adjustments could not fully capture. Adnan also notes that the study showed no significant difference in overall survival or progression-free survival, which supports the idea that shortening was not harmful but does not prove that shortened venetoclax is truly equivalent in efficacy. Prospective, ideally randomized validation remains the essential next step before practice changes on a wide scale.

There is a deeper conceptual problem as well, and it sits at the heart of the proposed framework. Bone marrow morphology, the century-old practice of examining stained marrow smears under a microscope, is functional and widely available, but it is a blunt instrument. It can miss small populations of leukemic cells that persist below the threshold of visual detection, and its interpretation varies between observers. The editorial contends that early marrow morphology is useful but insufficient on its own, and that relying on a single marker to decide whether to curtail a backbone therapy in a disease as heterogeneous as acute myeloid leukemia is inherently risky.

This is where measurable residual disease enters the picture. A consensus document from the European LeukemiaNet MRD Working Party, authored by Heuser and colleagues, established MRD as a central biomarker in acute myeloid leukemia, serving prognostic, predictive, monitoring, and efficacy-response functions. A positive or negative MRD result indicates whether quantifiable disease is detected above specific thresholds, but those thresholds differ depending on the assay and the laboratory performing it. Flow cytometry, polymerase chain reaction-based assays for mutations such as NPM1, and other techniques each carry distinct sensitivities and limitations, which means an MRD result must always be interpreted in context rather than treated as an absolute verdict.

Recognizing these limitations, recent work by Bancos and colleagues has advocated a multimodal approach to residual disease assessment, tracing the evolution from cytogenetics and molecular biology to emerging technologies such as methylation pattern analysis and surface-enhanced Raman scattering. Each molecular marker, whether marrow morphology, conventional MRD, or molecular MRD via next-generation sequencing, may contribute to diagnosis and monitoring, but none is individually sufficient to guide every treatment decision. The editorial takes this logic one step further and applies it specifically to the question of venetoclax duration, proposing that the integration of multiple markers could provide a more precise and personalized basis for deciding when to stop or shorten therapy.

The framework also draws inspiration from the broader multi-omics movement in hematology. A review by Soleimani Samarkhazan highlighted how integrating complementary molecular and transcriptomic indicators can enable more accurate response-adapted approaches in acute myeloid leukemia, potentially allowing venetoclax duration to be customized according to both morphological and biological measures of disease response. Under such a model, a patient whose marrow clears rapidly, whose MRD assays turn negative early, whose leukemic clone shows molecular responses on sequencing, and whose blood counts recover promptly might safely de-escalate to shorter venetoclax cycles. Conversely, a patient with persistent molecular evidence of disease might continue full-dose therapy or be considered for escalation, even if the microscope looks reassuringly empty.

The stakes of getting this right are considerable. Acute myeloid leukemia is a progressively increasing form of leukemia with consistently high incidence and mortality, imposing a growing strain on health systems worldwide. Projections based on the Global Burden of Disease Study 2021 estimate that by 2040 the number of cases will rise significantly, with predicted figures reaching approximately 184,287.88 for incidence and 165,537.59 for mortality. The economic toll is equally sobering: a United States analysis by Hagiwara and colleagues of 9,455 newly diagnosed patients found that the average healthcare cost per patient was 386,077 dollars. Every day of unnecessary venetoclax exposure adds hospitalizations, growth factor use, transfusions, and infection management to that bill, while every day of insufficient exposure risks relapse, which is far more expensive and far more deadly.

What makes the editorial’s proposal compelling is that it reframes a question the field has been circling for years. Venetoclax-based regimens have delivered unprecedented response rates in unfit patients, but the drug’s hallmark toxicity, myelosuppression, has remained a stubborn constraint, and clinicians have lacked a principled way to know when enough is enough. By proposing a multi-marker panel that unites marrow morphology, MRD, molecular MRD via next-generation sequencing, and hematologic recovery, the editorial sketches a route toward treating venetoclax duration the way modern oncology treats nearly everything else: as a variable to be tuned by data rather than fixed by tradition. The author acknowledges the constraints of the underlying evidence, including the retrospective design of the pivotal real-world study and the possibility that no single marker can capture the full complexity of the disease. But the direction of travel is clear, and the call for prospective research into a multi-marker response-adapted framework gives the field a concrete hypothesis to test. If randomized studies confirm that response-guided shortening preserves survival while stripping away toxicity, the fixed ten-plus-month venetoclax paradigm could give way to something smarter, safer, and genuinely personal, and the editorial argues that the tools to build that future are already on the laboratory bench.

Subject of Research: Response-adapted venetoclax dosing guided by multi-marker disease assessment in acute myeloid leukemia

Article Title: Presenting a multi-marker response-adapted framework for venetoclax duration in acute myeloid leukemia

Article References: Adnan, N. (2026). Presenting a multi-marker response-adapted framework for venetoclax duration in acute myeloid leukemia. Annals of Hematology, 105(10), Article 414. https://doi.org/10.1007/s00277-026-07280-x

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07280-x

Keywords: acute myeloid leukemia, venetoclax, measurable residual disease, bone marrow morphology, next-generation sequencing, BCL-2 inhibitor, neutropenia, response-adapted therapy, multi-omics, hematology, treatment de-escalation, European LeukemiaNet