The study’s technical innovation lies in separating two DNA modifications that standard tools cannot distinguish. The most common epigenetic mark, 5-methylcytosine, or 5mC, typically silences gene expression when it appears in promoter regions. Under the action of TET enzymes, 5mC can be oxidized into 5-hydroxymethylcytosine, or 5hmC, a demethylation intermediate that often has the opposite effect and may activate genes. Traditional bisulfite sequencing, the workhorse of DNA methylation research, converts unmethylated cytosines to uracil but leaves both 5mC and 5hmC untouched, so the resulting measurement is actually a composite of the two marks. To untangle them, the researchers ran two parallel assays on the same DNA samples: targeted bisulfite sequencing to capture the combined signal, and APOBEC-coupled epigenetic sequencing, which uses an enzyme to label hydroxymethylated cytosines with glucose so they survive deamination while methylated and unmodified cytosines are converted. Subtracting the hydroxymethylation level from the composite level yielded what the team calls true methylation.

The study population was drawn from two established Chinese cohorts. Cases came from the China Antihypertensive Trial in Ischemic Stroke, a multicenter randomized trial of blood pressure management after stroke, from which 615 patients with imaging-confirmed ischemic stroke were selected. Controls, totaling 610 individuals, were frequency-matched by age and sex from the Prevention of Metabolic Syndrome and Multi-Metabolic Disorders Study, a community-based prospective cohort. The participants averaged 62 years of age, with roughly equal numbers of men and women in each group. As expected, stroke patients carried a heavier burden of metabolic risk factors, including hypertension, diabetes, obesity, hyperglycemia, and dyslipidemia, and the two groups also differed in education level. These characteristics were carefully accounted for in the statistical models, which adjusted for age, sex, education, smoking, drinking, body mass index, blood lipids, hypertension, and diabetes.

The target region spanned nine CpG sites in the NPPA promoter, located between 540 and 276 base pairs upstream of the transcription start site on chromosome 1. Genomic DNA extracted from peripheral blood mononuclear cells was processed through both sequencing pipelines, with stringent quality control: samples showing bisulfite conversion rates below 98 percent or average sequencing coverage under 20-fold were excluded. The nine CpG sites were then analyzed individually and collectively. For the gene-level analysis, the researchers employed the weighted truncated product method, which combines P values across multiple sites while weighting each by its regression coefficient, a strategy designed to detect joint effects that individual site analyses might miss when each contributes only a small share of the overall signal.

The methylation results were striking. At eight of the nine CpG sites, true methylation levels were significantly lower in stroke patients than in controls, and this hypomethylation was negatively associated with the risk of having an ischemic stroke. These associations survived correction for multiple testing using the false discovery rate approach, with all q values below 0.05. When the nine sites were considered together, the gene-based association was significant, and the mean methylation level across the region showed a clear dose-response relationship: each unit increase in mean true methylation corresponded to an odds ratio of 0.94 for stroke, with a 95 percent confidence interval of 0.91 to 0.97. Subgroup analyses revealed that the association was more pronounced among older participants, women, non-smokers, non-drinkers, and those with lower educational attainment, findings the authors suggest could guide the clinical application of epigenetic markers.

Hydroxymethylation told a different and more nuanced story. Although median hydroxymethylation levels at the assayed sites tended to be higher in stroke patients, only one CpG site, designated CpG2 and located at chromosome 1 position 11,908,348, showed a statistically significant positive association with stroke after covariate adjustment and multiple testing correction, with an odds ratio of 1.39 and a 95 percent confidence interval of 1.15 to 1.68. The gene-based test for hydroxymethylation was also significant, indicating a joint effect across the region, but the mean hydroxymethylation level alone did not distinguish cases from controls. Notably, CpG2 was the only site where both methylation and hydroxymethylation were independently associated with stroke, making it a particularly intriguing candidate for future precision interventions if the relevant technologies mature.

Beyond stroke risk, the researchers asked whether these epigenetic marks could predict recovery. They followed 598 of the 615 stroke patients, after excluding 17 lost to follow-up, and assessed functional outcome at three months using the modified Rankin Scale, an ordinal measure ranging from no symptoms to death. In ordered logistic regression models that additionally adjusted for stroke subtype, time from onset to hospitalization, stroke severity on the National Institutes of Health Stroke Scale, and treatment assignment, true methylation levels at all eight significant CpG sites were associated with a lower risk of scoring higher on the scale, meaning better neurological recovery. A complementary binary analysis defining poor outcome as a modified Rankin Scale score of 3 or higher produced consistent results. Hydroxymethylation, by contrast, showed no significant association with functional outcome at any site, and the gene-based test for hydroxymethylation and outcome was not significant.

The findings fit into a broader scientific context. Circulating ANP levels have previously been linked to ischemic stroke and to 90-day mortality and functional outcomes after stroke onset, and genetic variants in NPPA have been associated with both ANP levels and stroke susceptibility in studies of Chinese and Korean populations. Because promoter methylation generally suppresses gene expression, the observed hypomethylation in stroke patients is consistent with reports that stroke patients carry higher serum ANP levels, though the authors caution that a direct causal link between NPPA promoter methylation and ANP expression has not yet been verified; in their own earlier work, methylation at these same sites did not significantly predict serum proANP levels. Animal studies add another layer: mice experiments have shown that 5hmC can protect the brain from ischemic injury, and knockdown of the TET enzymes that generate 5hmC worsened brain degeneration in models of focal ischemia.

The study’s implications reach toward prevention and treatment. Because epigenetic modifications are chemically reversible, unlike fixed genetic variants, the CpG sites identified here could serve not only as biomarkers for risk stratification and prognosis but also as potential therapeutic targets. This is particularly relevant given the troubled history of ANP-targeted drugs such as sacubitril/valsartan and recombinant carperitide, whose clinical use has been limited by hypotension, angioedema, and fatalities in hospital settings. A deeper understanding of how the NPPA gene is regulated at the epigenetic level might open alternative routes to modulating the ANP pathway more safely.

The authors are careful to note the limitations of their work. As an observational study, it cannot determine whether altered methylation and hydroxymethylation in the NPPA promoter are causes, consequences, or mere companions of ischemic stroke. Residual confounding cannot be fully excluded despite extensive adjustment, and the findings, derived from Chinese adults, may not generalize to other ethnic or age groups. The absence of circulating ANP measurements in the current dataset leaves the mechanistic bridge between promoter marks and hormone levels unconfirmed. Nevertheless, by simultaneously quantifying true methylation and hydroxymethylation at identical CpG sites in a large case-control sample with prospective follow-up, the study demonstrates that the two marks carry distinct information about stroke risk and recovery, and it makes a compelling case that separating them should become standard practice in epigenetic epidemiology of complex disease.

Subject of Research: Associations of NPPA promoter DNA methylation and hydroxymethylation with ischemic stroke risk and functional outcome

Article Title: Associations of NPPA promoter true methylation and hydroxymethylation with ischemic stroke and its functional outcome

Article References: Yao, J., Song, L., Jiang, J., Zhang, J., Chen, L., Fan, W., Lu, Y., Zhang, X., Jing, J., Jin, Y., Zhang, M., Hao, Y., & Peng, H. (2024). Associations of NPPA promoter true methylation and hydroxymethylation with ischemic stroke and its functional outcome. Epigenetics Communications, 4(1), Article 6. https://doi.org/10.1186/s43682-024-00029-5

Image Credits: AI Generated

DOI: 10.1186/s43682-024-00029-5

Keywords: ischemic stroke, NPPA, atrial natriuretic peptide, DNA methylation, DNA hydroxymethylation, epigenetics, bisulfite sequencing, APOBEC-coupled epigenetic sequencing, modified Rankin Scale, functional outcome, biomarkers, case-control study

The tool in question is the FUNC score, short for the Functional Outcome in Patients with Primary Intracerebral Hemorrhage score, developed by neurologists at Massachusetts General Hospital and first published in the journal Stroke in 2008. The score distills a handful of variables available at hospital admission — the volume and location of the bleed on initial imaging, the patient’s age, the Glasgow Coma Scale score on arrival, and whether the patient was already taking an anticoagulant medication such as warfarin — into a single number ranging from zero to eleven. In its original validation, the score predicted whether patients would achieve functional independence, defined as a Glasgow Outcome Scale score of four or higher, ninety days after the hemorrhage. That three-month window, however, has increasingly been recognized as an arbitrary snapshot of what is often a much longer recovery.

Recovery after brain injury is not a fixed event but a moving target. Emerging evidence, including a growing body of work on recovery trajectories after intracerebral hemorrhage, shows that many patients continue to improve between three and twelve months after the bleed. In some cohorts, a meaningful proportion of survivors who were dependent at three months walk, feed themselves, and manage their own affairs a year later. If clinicians base early prognostic conversations only on tools validated at three months, they risk anchoring families to an overly pessimistic view — or, conversely, they may lack the statistical justification to make confident statements about long-term independence at all. Recognizing this gap, a team led by Joel Neves Briard, a postdoctoral researcher in Columbia’s Department of Neurology, and senior author Jan Claassen, professor of neurology and critical care specialist, set out to ask whether the FUNC score could be stretched, without distortion, to a twelve-month horizon.

The team conducted a single-center prospective cohort study, enrolling adult patients admitted with primary intracerebral hemorrhage between February 2009 and January 2018. Prospective enrollment matters in this kind of research: rather than reconstructing cases from medical records after the fact, investigators collected structured data on patients as they arrived and followed them forward, reducing the bias and missingness that plague retrospective analyses. All patients included in the analysis had a primary hemorrhage — meaning the bleed was not secondary to trauma, aneurysm rupture, or vascular malformation — and each patient’s FUNC score was calculated at admission using the same variables that have anchored the score since its debut. Twelve months later, surviving patients’ functional status was assessed using the Glasgow Outcome Scale, a five-point measure that ranges from death to good recovery and that classifies patients scoring four or five as broadly independent.

The cohort ultimately comprised 535 patients, a substantial sample for this disease. The patients were, on average, seriously ill: their median age was 68 years, 44 percent were women, and the median National Institutes of Health Stroke Scale score at presentation was 16, a level indicating moderate to severe neurological impairment. Median FUNC score in the cohort was 8 on the eleven-point scale. Among the 445 patients with a known Glasgow Outcome Scale assessment at twelve months, 99 — roughly 22 percent — had achieved functional independence. That figure alone carries a message for families: even in a cohort skewing severely ill, more than one in five patients was living independently a year after a brain bleed, a reminder that early appearances can mislead.

The statistical heart of the study lay in testing whether the FUNC score’s predictions still held at one year. The researchers used logistic regression to calculate the area under the receiver operating characteristic curve, or AUC, the standard gauge of a prediction model’s ability to separate those who will experience an outcome from those who will not. An AUC of 0.5 indicates performance no better than a coin flip, while 1.0 represents perfect discrimination. For twelve-month functional independence, the FUNC score achieved an AUC of 0.79, with a 95 percent confidence interval of 0.75 to 0.84 — a level of discrimination broadly comparable to the score’s originally validated three-month performance. In practical terms, the score’s simple admission-time arithmetic remained nearly as informative about the one-year future as about the three-month one.

Discrimination, however, is only half the story. A model can rank patients correctly yet still misjudge how likely the outcome actually is, which is why the researchers also evaluated calibration — the agreement between predicted probabilities and observed frequencies — using a calibration plot, alongside the Brier score, a composite measure of both discrimination and calibration that penalizes confident wrong answers. The calibration plot showed reasonable agreement between predicted and observed outcomes across the probability range, with modest evidence that the score slightly overestimated the likelihood of independence at the low end of predicted probabilities. The Brier score came in at 0.15, a respectable figure for a binary clinical outcome. To address the patients lost to follow-up, the team handled missing twelve-month outcomes using multiple imputation by chained equations, a modern statistical technique that fills gaps by modeling each incomplete variable conditional on all others, preserving uncertainty rather than pretending missing data do not exist.

Finally, the investigators asked a question that has become central to the modern evaluation of clinical prediction tools: does the score actually help make decisions? Using decision curve analysis, a method developed by Vickers and Elkin that quantifies the net clinical benefit of acting on a model’s predictions across a range of risk thresholds, the team found that the FUNC score delivered measurable net benefit across threshold probabilities from 5 to 50 percent. In other words, within the range of probabilities most relevant to real clinical conversations, basing decisions on the score beat both the strategy of assuming every patient will be independent and the strategy of assuming none will be — the two extremes any prognostic tool must outperform to be worth the bedside clinician’s attention.

The implications reach beyond the family meeting. The authors point to two principal applications. The first is counseling: armed with a validated twelve-month prediction, clinicians can offer families a more honest account of long-term prospects, tempering the nihilism that has historically shadowed intracerebral hemorrhage care. This matters because premature withdrawal of life-sustaining therapy, driven in part by excessively pessimistic early prognostication, remains a documented concern in hemorrhagic stroke, and formal guidelines for neuroprognostication in critically ill adults with intracerebral hemorrhage explicitly caution against self-fulfilling prophecies. The second application is methodological. The FUNC score can support sliding dichotomy, a trial-design strategy in which the outcome threshold for success is adjusted to each patient’s predicted baseline risk — an approach pioneered in traumatic brain injury research that increases statistical power by recognizing that a modest recovery for the sickest patients may be as meaningful as a full recovery for the mildest ones.

The researchers are careful about limits. This was a single-center study at a major academic medical center, and prediction models notoriously lose calibration when transplanted to different populations and care environments; external validation across centers is needed before the twelve-month FUNC score becomes standard practice. The field’s own reporting standards, codified in the TRIPOD+AI statement for clinical prediction models, demand exactly this kind of transparency about performance, calibration, and intended use. Still, the study’s message is striking in its simplicity. A tool invented nearly two decades ago, computed from five variables a clinician can gather before the patient has even reached the intensive care unit, appears to hold its predictive power across the full year in which the brain does its slow, stubborn work of healing. For the families sitting in hospital corridors, that is not just a statistical achievement — it is a reason to keep asking the question, and to keep hoping the answer changes.

Subject of Research: Prediction of 12-month functional independence after primary intracerebral hemorrhage using the FUNC score

Article Title: Extension of the FUNC Score for Prediction of 12-Month Functional Independence after Primary Intracerebral Hemorrhage

Article References: Extension of the FUNC Score for Prediction of 12-Month Functional Independence after Primary Intracerebral Hemorrhage. (n.d.). https://doi.org/10.1007/s12028-026-02661-6

Image Credits: AI Generated

DOI: 10.1007/s12028-026-02661-6

Keywords: intracerebral hemorrhage, stroke, FUNC score, prognostication, functional outcome, Glasgow Outcome Scale, neurocritical care, prediction model, recovery, brain bleed, Extension, FUNC

The study drew on the German Stroke Registry–Endovascular Treatment (GSR-ET), a prospective, multicenter registry spanning 25 comprehensive stroke centers across Germany. Between June 2015 and December 2023, more than 18,000 patients were screened, and after excluding those with extracranial carotid occlusions, pre-stroke disability, or missing key clinical data, 5,448 patients treated with mechanical thrombectomy for anterior circulation strokes formed the analytical cohort. The mean age was 71.2 years, 48 percent were women, and the median stroke severity on admission, measured by the National Institutes of Health Stroke Scale (NIHSS), was 13. The researchers stratified patients into nine subgroups based on admission NIHSS (0–10, 11–15, or ≥16) and the Alberta Stroke Program Early CT Score (ASPECTS), a ten-point measure of early infarct signs on CT imaging (10, 8–9, or ≤7).

This dual stratification was designed to capture what neurointerventionalists call clinical-core mismatch. The concept is elegant: a patient whose neurological deficit is dramatically worse than the visible extent of infarction likely has a large penumbra, a zone of struggling but still salvageable brain tissue, whereas a patient whose symptoms are mild relative to a large established infarct has less to gain from reopening the vessel. The DAWN and DEFUSE-3 trials famously demonstrated that patients with pronounced mismatch benefit from thrombectomy even in extended time windows of up to 24 and 16 hours, respectively. But those trials used sophisticated perfusion imaging and volumetric core measurements. The new study instead used the readily available NIHSS and ASPECTS scores as a clinical surrogate, testing whether the same pattern holds in the messy reality of routine practice.

The results were striking. Reperfusion success was graded using the modified Thrombolysis in Cerebral Infarction (mTICI) scale: 650 patients achieved minimal or no reperfusion (mTICI 0–2a), 1,873 achieved partial reperfusion (mTICI 2b), and 2,925 achieved complete recanalization (mTICI 3). Unadjusted outcomes followed a steep gradient: only 20 percent of patients with failed reperfusion achieved functional independence, defined as a modified Rankin Scale (mRS) score of 0 to 2 at 90 days, compared with 46 percent after partial reperfusion and 54 percent after complete recanalization. Mortality at 90 days told the same story in reverse, at 39 percent, 20 percent, and 17 percent respectively. Symptomatic intracranial hemorrhage, a feared procedural complication, occurred in 5 percent of failed reperfusion cases but only 2 percent of complete recanalizations.

Because patients who achieve full recanalization may differ systematically from those who do not, the researchers applied inverse-probability-weighted regression adjustment (IPWRA), a double-robust statistical technique that controls for confounders such as age, sex, comorbidities, baseline NIHSS and ASPECTS, intravenous thrombolysis, and the number of retrieval attempts. The adjusted estimates confirmed the pattern: 25 percent good outcomes after mTICI 0–2a, 46 percent after mTICI 2b, and 52 percent after mTICI 3, with adjusted mean mRS scores of 4.0, 3.0, and 2.7 respectively. Crucially, significant benefit from successful reperfusion was observed in every one of the nine NIHSS-ASPECTS subgroups, including patients with large established infarcts and those with only mild symptoms.

The size of that benefit, however, varied dramatically. The clearest beneficiaries were patients with high clinical-core mismatch, particularly those with a perfect ASPECTS of 10 and severe deficits (NIHSS ≥16). In this group, only 9 percent of patients with failed reperfusion achieved functional independence, compared with 47 percent after complete recanalization, an absolute difference of 38 percentage points. Patients with moderate deficits (NIHSS 11–15) and ASPECTS 10 showed comparable gains. At the opposite extreme, patients with severe deficits and extensive infarct signs (NIHSS ≥16, ASPECTS ≤7) saw a much smaller but still significant benefit, with good outcomes rising from 12 percent to 23 percent, an absolute difference of 11 percentage points. The exploratory mRS shift analysis reinforced the pattern, showing the largest disability reduction, nearly two full mRS points, in the ASPECTS 10 and NIHSS 11–15 subgroup.

One of the most clinically consequential findings concerned the difference between near-complete and complete reperfusion. Pushing from mTICI 2b to mTICI 3 often requires additional retrieval attempts, each carrying a risk of vessel perforation, dissection, or distal clot migration. The data showed that the extra benefit of full recanalization was concentrated in high-mismatch patients: in the NIHSS ≥16, ASPECTS 10 subgroup, complete recanalization lifted good outcomes from 32 percent to 47 percent, a 15-point gain. But in patients with large infarcts (NIHSS ≥16, ASPECTS ≤7), outcomes were essentially identical after mTICI 2b and mTICI 3, both around 20 percent. The authors suggest that in selected low-mismatch cases, accepting mTICI 2b as an adequate procedural endpoint may be a pragmatic choice that avoids unnecessary procedural risk.

The findings also complicate the emerging picture from randomized trials. Recent studies such as SELECT2, ANGEL-ASPECT, RESCUE-Japan LIMIT, and TENSION demonstrated that even patients with large established infarcts benefit from thrombectomy, expanding treatment beyond the classic mismatch paradigm. Meanwhile, a post-hoc analysis of ANGEL-ASPECT failed to show benefit in patients stratified by clinical-radiological mismatch, and recent trials in distal medium vessel occlusions have questioned whether mismatch concepts translate uniformly across vascular territories. The new registry data reconcile some of this tension: mismatch profiles appear to modify the size of the treatment effect rather than determine whether treatment helps at all. In other words, clinical-core mismatch should inform expectations and procedural goals, not serve as a rigid gatekeeper for eligibility.

The authors are careful to note important limitations. Roughly 70 percent of screened patients were excluded in the complete-case analysis because of missing variables, a substantial selection process that may bias effect estimates and limit generalizability to unselected populations. Patients with pre-stroke disability were excluded, local investigators rather than a central core lab graded ASPECTS and mTICI, and unmeasured factors such as collateral circulation, infarct location, and time from onset to imaging could not be fully accounted for. The use of linearized mRS scores in exploratory analyses also assumes equal spacing between scale points, an assumption that may not fully hold. These caveats mean the findings in mild stroke and low-ASPECTS groups should be considered exploratory, even as the high-mismatch results align closely with prior randomized evidence.

Looking forward, the study points toward a more individualized era of stroke treatment. Rather than fixed subgroup thresholds, the authors argue that outcome effects across ASPECTS likely follow a continuous gradient, and future selection tools may integrate advanced imaging biomarkers such as net water uptake, a quantitative measure of early brain swelling, to estimate each patient’s likely benefit from reperfusion. For now, the message for clinicians is nuanced but actionable: successful reperfusion helps virtually every patient profile, but the magnitude of benefit is greatest when a severe deficit signals a large salvageable penumbra, and the pursuit of complete recanalization matters most precisely in those patients. In resource-limited settings where every thrombectomy counts, that distinction could help ensure the right patients receive the most aggressive endovascular effort.

Subject of Research: Reperfusion-dependent outcomes after endovascular thrombectomy for acute ischemic stroke, stratified by NIHSS-ASPECTS clinical-core mismatch

Article Title: Reperfusion‐Dependent Outcomes After Endovascular Thrombectomy Stratified by NIHSS‐ASPECTS Clinical‐Core Mismatch

Article References: Schlicht, F., Meyer, L., Broocks, G., Bechstein, M., Thaler, C., Heitkamp, C., Winkelmeier, L., Geest, V., Heitkamp, A., Jungnitz, M., Peter, G., Meucci, L., Faizy, T., Nawabi, J., Brekenfeld, C., Flottmann, F., Schell, M., Hadjilaou, A., Hanning, U., … German Stroke Registry Endovascular Treatment (2026). Reperfusion‐Dependent Outcomes After Endovascular Thrombectomy Stratified by NIHSS ‐ ASPECTS Clinical‐Core Mismatch. Annals of Clinical and Translational Neurology, 13(9), 1807-1816. https://doi.org/10.1002/acn3.70358

Image Credits: AI Generated

DOI: 10.1002/acn3.70358

Keywords: mechanical thrombectomy, acute ischemic stroke, reperfusion, clinical-core mismatch, NIHSS, ASPECTS, mTICI, functional outcome, German Stroke Registry, large vessel occlusion, penumbra, neurointervention