The most striking quantitative claim in the review concerns scale. Systematic sequencing cohorts suggest that up to 20 to 35 percent of children with aplastic anemia or pediatric myelodysplastic syndrome harbor an underlying germline mutation, meaning a significant proportion of cases initially classified as acquired marrow failure are in fact inherited. Next-generation sequencing has expanded the recognized disease spectrum accordingly. The clinical stakes of this distinction are high: immunosuppressive therapy with antithymocyte globulin and cyclosporine, the standard first-line treatment for acquired aplastic anemia, is not only ineffective in inherited syndromes but potentially harmful. In telomere biology disorders, many patients carry an occult T-cell immunodeficiency independent of overt marrow failure, so ATG-based immunosuppression can precipitate life-threatening infections. In Fanconi anemia, exposure to DNA-damaging agents carries serious risks, and inappropriate conditioning regimens before transplant are associated with significantly increased toxicity and mortality.

Epidemiologically, the combined incidence of the classic inherited bone marrow failure syndromes is estimated at approximately one in 15,000 live births, or 64.5 cases per million births in the largest population-based cohort to date, a figure the authors note likely underestimates true prevalence. Many affected individuals present with mild, isolated, or slowly progressive cytopenias and are diagnosed only in later childhood, adolescence, or even adulthood. In syndromes with incomplete penetrance or late-onset hematologic manifestations, most notably telomere biology disorders and GATA2 deficiency, recognition may be further delayed by the absence of overt congenital features. The malignant risk varies considerably across syndromes: in Fanconi anemia the cumulative incidence of bone marrow failure, MDS/AML, or solid malignancy approaches 90 percent by age 50, with MDS/AML specifically estimated at roughly 30 percent by age 40; GATA2 deficiency carries approximately 70 percent risk of transformation by age 70, and Shwachman-Diamond syndrome approximately 30 to 35 percent lifetime.

Despite their genetic diversity, the syndromes share a common pathogenetic outcome: progressive exhaustion of hematopoietic stem cell self-renewal and differentiation capacity, creating selective pressure for clonal evolution. Three principal molecular pathways are affected. Fanconi anemia, the prototypical DNA repair disorder, results from biallelic mutations in genes of the FA/BRCA pathway responsible for resolving DNA interstrand crosslinks caused by endogenous aldehydes and exogenous genotoxins; 23 complementation groups are now known, including the recently described FANCX/FAAP100, although FANCB is X-linked and FANCR/RAD51 autosomal dominant. Telomere biology disorders arise from mutations in at least 16 genes encoding telomerase components or telomere-protective proteins, accelerating telomere attrition and premature senescence in the high-turnover hematopoietic compartment. Diamond-Blackfan anemia and Shwachman-Diamond syndrome are ribosomopathies, in which impaired ribosome biogenesis activates p53-dependent stress pathways and drives apoptosis of blood cell progenitors.

Clinical presentation is remarkably heterogeneous, ranging from mild cytopenias found incidentally to severe pancytopenia in infancy. Macrocytosis is a helpful early clue in several syndromes, but the review cautions that it should be judged against age-specific pediatric reference ranges rather than a fixed adult threshold, and that its absence does not exclude an inherited cause. Diamond-Blackfan anemia typically presents within the first year of life with severe macrocytic anemia and reticulocytopenia, with congenital anomalies in roughly half of patients, including craniofacial defects and typically triphalangeal rather than absent thumbs. Shwachman-Diamond syndrome begins with chronic neutropenia alongside exocrine pancreatic insufficiency and metaphyseal skeletal dysplasia. Congenital amegakaryocytic thrombocytopenia presents at or shortly after birth with isolated severe thrombocytopenia and absent megakaryocytes, while severe congenital neutropenia produces profound neutropenia, typically below 0.2 x 10^9 per liter, with recurrent bacterial infections from the first months of life.

GATA2 deficiency occupies its own pathogenetic category as a transcription factor disorder. Haploinsufficiency of GATA2 produces a stereotyped pattern of selective cytopenias, nearly universal monocytopenia with depletion of B and NK lymphocytes, while neutrophil counts are often preserved until late. This immunological signature predisposes to disseminated nontuberculous mycobacterial infection, invasive fungal disease, and HPV-associated disease, and infection episodes may precede overt cytopenia. Mechanistically, GATA2 deficiency is linked to SAMD9/SAMD9L-related disorders through shared chromosome 7 instability. Germline gain-of-function mutations in these adjacent interferon-regulated genes cause excessive antiproliferative signaling, and hematopoietic clones frequently rescue themselves by losing the mutant allele through monosomy 7, uniparental disomy of 7q, or a second inactivating mutation. This somatic genetic rescue explains historically puzzling transient monosomy 7 in young children and links these germline defects to a substantial proportion of pediatric MDS with monosomy 7.

Clonal evolution in these syndromes is biologically distinct from age-related clonal hematopoiesis, and different clones carry very different prognoses. Somatic mutations in TP53, RUNX1, and ASXL1 indicate high malignant risk. In Fanconi anemia, gain of chromosome 1q is the most common and earliest route to clonal dominance, while cryptic RUNX1 mutations constitute a later leukemogenic pathway found in up to one-fifth of patients. In GATA2 deficiency, monosomy 7 and trisomy 8 occur in roughly 70 and 24 percent of mutation carriers respectively. In Shwachman-Diamond syndrome, isochromosome 7q may be relatively indolent whereas monosomy 7 confers high risk, and somatic EIF6 mutations or del(20q) appear compensatory, while biallelic TP53 alterations mark a maladaptive path. In severe congenital neutropenia, a two-step model predominates: truncating CSF3R mutations arise first under chronic G-CSF exposure, followed often years later by RUNX1 mutations marking imminent transformation.

Diagnosis rests on layered testing. Chromosomal breakage testing with diepoxybutane or mitomycin C remains the gold standard for Fanconi anemia and is recommended in children with unexplained marrow failure, ideally before or alongside broader sequencing. Targeted germline next-generation sequencing panels covering all known syndrome genes are recommended as first-line genetic evaluation where available, and lymphocyte telomere length below the first percentile by flow-FISH should trigger sequencing of the full telomere biology disorder gene panel rather than a limited subset. The review also details the limitations of sequencing: short-read panels have reduced sensitivity for structural variants such as ribosomal protein gene deletions, which account for an estimated 10 to 15 percent of pathogenic variants across this gene set; non-coding variants require genome sequencing or RNA assays; and variants of uncertain significance should never alone confirm a diagnosis, guide donor selection, or alter conditioning intensity. Testing is best performed on non-hematopoietic tissue such as cultured skin fibroblasts, since somatic reversion in blood can mask the germline variant.

Management is syndrome-specific, with hematopoietic stem cell transplantation the only curative option for the hematologic component. Timing is an area of active controversy: outcomes in Fanconi anemia are best when transplantation precedes MDS development, pre-emptive transplant is increasingly supported in GATA2 deficiency and high-risk Shwachman-Diamond syndrome, CAMT transplantation is generally undertaken once a donor is identified, whereas in SAMD9/SAMD9L syndrome close surveillance for spontaneous somatic rescue may be preferable to immediate transplantation in young children with monosomy 7. Conditioning must be individualized, with reduced-intensity fludarabine-based regimens favored in Fanconi anemia and telomere biology disorders, and myeloablative conditioning preferred when feasible in GATA2 deficiency. Related donors require germline screening, since an unrecognized carrier sibling can transfer the disease into the graft. Because transplant corrects only the hematologic compartment, solid malignancy risk persists in non-hematopoietic tissues, underscoring lifelong surveillance.

The review closes with emerging therapeutic prospects. Gene therapy has advanced furthest in Fanconi anemia, where autologous lentiviral correction of FANCA in CD34-positive stem cells, requiring no cytotoxic conditioning, has shown durable vector-marked engraftment and reversal of bone marrow failure in a majority of treated patients in phase 1/2 and long-term follow-up data, with no genotoxic events reported to date. Gene editing in Fanconi anemia faces a distinctive obstacle, since conventional CRISPR-Cas9 correction relies on the very FA repair pathway the therapy aims to restore, prompting workarounds using non-homologous end joining and base or prime editing. Eltrombopag has produced hematologic responses in small series of steroid-refractory Diamond-Blackfan anemia, though robust evidence remains lacking, and error-corrected deep sequencing is improving clonal risk stratification. The authors emphasize that realizing this potential will require prospective international registries and collaborative trials to build the evidence base still lacking for many of these rare conditions.

Subject of Research: Inherited bone marrow failure syndromes in children, their genetic causes, diagnosis, clonal evolution, and management including hematopoietic stem cell transplantation

Article Title: Inherited bone marrow failure syndromes in childhood: clinical presentation, diagnostic approach, and contemporary management

Article References: Ivančan, S., & Jazbec, J. (2026). Inherited bone marrow failure syndromes in childhood: clinical presentation, diagnostic approach, and contemporary management. Frontiers in Pediatrics, 14, Article 1909640. https://doi.org/10.3389/fped.2026.1909640

Image Credits: AI Generated

DOI: 10.3389/fped.2026.1909640

Keywords: inherited bone marrow failure syndromes, Fanconi anemia, telomere biology disorders, GATA2 deficiency, Diamond-Blackfan anemia, Shwachman-Diamond syndrome, SAMD9/SAMD9L, clonal evolution, next-generation sequencing, pediatric MDS, hematopoietic stem cell transplantation, gene therapy