Fanconi anemia complementation group A results from biallelic pathogenic variants in FANCA, located on chromosome 16 (per GeneReviews). FANCA encodes a protein integral to the Fanconi anemia DNA damage response pathway, which repairs interstrand DNA cross-links and maintains genomic stability. The ClinGen Expert Panel has classified the FANCA-Fanconi anemia disease association as DEFINITIVE. FA-A follows autosomal recessive inheritance. Per GeneReviews, null (loss-of-function) FANCA variants generally produce a more severe phenotype including earlier-onset bone marrow failure and higher leukemia incidence than hypomorphic variants that permit partial protein production. Individuals with biallelic or heterozygous FANCA pathogenic variants in the exon 27-30 C-terminal domain face dramatically elevated solid tumor risk, approaching 100% by age 45 years, compared with 25-50% in those with FANCA pathogenic variants located elsewhere (per GeneReviews). FANCA founder pathogenic variants have been documented in Afrikaners, Moroccan Israeli Jews, and Spanish Romani populations.

Per GeneReviews, the diagnosis of Fanconi anemia is established by one of two approaches: chromosomal breakage testing of lymphocytes using diepoxybutane (DEB) and/or mitomycin C (MMC) demonstrating increased breakage and characteristic radial chromosome forms, or molecular genetic testing identifying biallelic FANCA pathogenic variants. DEB is the preferred agent at many centers, as background breakage rates in control chromosomes show greater variability with MMC alone. When lymphocyte results are normal or inconclusive with suspected somatic mosaicism, skin fibroblast testing may be used as an alternative cell source. Molecular genetic testing approaches include single-gene sequence analysis of FANCA followed by deletion/duplication analysis if sequencing is non-informative, multigene panel testing, or comprehensive genomic testing. Clinical findings that raise diagnostic suspicion include short stature, abnormal skin pigmentation, thumb or radial malformations, microcephaly, genitourinary anomalies, macrocytosis, elevated fetal hemoglobin, and progressive cytopenia. Inordinate toxicity from chemotherapy or radiation in a patient with cancer is also a recognized presentation that warrants FA evaluation (per GeneReviews).

No FDA-approved pharmacotherapy specifically for FA-A has been identified in this packet. Per GeneReviews, the primary targeted therapies for hematologic manifestations of FA include androgens, granulocyte colony-stimulating factor (G-CSF), and hematopoietic stem cell transplantation (HSCT). Androgenic agents including oxymetholone, stanozolol, oxandrolone, and danazol transiently improve red blood cell and platelet counts in approximately 50% of treated individuals; per GeneReviews, androgen therapy is considered when hemoglobin drops below 8 g/dL or platelet count falls below 30,000/mm3. G-CSF improves neutrophil counts in some individuals, is titrated to the lowest effective dose to maintain absolute neutrophil count above 1,000/mm3, and is administered in consultation with FA experts given the theoretical risk of stimulating a leukemic clone; bone marrow assessment is performed before initiation. HSCT is the only curative therapy for the hematologic manifestations of FA including aplastic anemia, MDS, and AML, and per GeneReviews is ideally performed before MDS/AML onset and before multiple transfusions. An investigational lentiviral gene therapy (Fancalen, Rocket Pharmaceuticals) has received FDA orphan drug designation specifically for FA type A.

Per GeneReviews, the clinical course of FA-A involves progressive bone marrow failure with risk of life-threatening cytopenia and malignant transformation, with rate and severity varying significantly by specific FANCA variant. Null FANCA variants are associated with earlier-onset anemia and higher leukemia incidence compared with hypomorphic variants. Individuals with FANCA pathogenic variants in the exon 27-30 C-terminal domain face dramatically elevated solid tumor burden approaching 100% by age 45 years compared with 25-50% in individuals with other FANCA pathogenic variants. Solid tumor risks include squamous cell carcinomas of the head and neck, esophagus, and vulva, and liver tumors in those who received androgen therapy. HSCT, while curative for hematologic manifestations, does not eliminate solid tumor risk and may contribute to endocrine complications and growth impairment when administered before closure of growth plates (per GeneReviews). Gynecologic examinations for genital lesions begin at age 13, per GeneReviews surveillance guidelines.

Active clinical research in FA-A spans gene therapy, HSCT optimization, and cancer surveillance. An investigational lentiviral gene therapy (Fancalen, Rocket Pharmaceuticals) carries FDA orphan drug designation specifically for FA type A. Per GeneReviews, early-phase gene therapy trials using lentiviral vectors for FANCA have been conducted at multiple international sites, though several are no longer actively recruiting. Among current registered trials: NCT05687149 (Defining the Natural History of Squamous Cell Carcinoma in FA, NCI, recruiting through 2035); NCT07408583 (Prenatal Transplantation for Fetuses With FA, Phase 1, not yet recruiting); NCT06648096 (Afatinib in FA patients with head and neck squamous cell carcinoma, Phase 1, recruiting through 2028); NCT06744283 (Cancer Screening-Related Anxiety in FA, NCI, recruiting); and NCT00027274 (Cancer in Inherited Bone Marrow Failure Syndromes, NCI, recruiting since 2001). The research landscape for this packet comprises 80 classified publications, with basic science and preclinical work as the dominant type, alongside gene therapy and biomarker research. No patient advocacy organizations were identified in this packet.