Purpose: Fanconi anemia is a genotypically and phenotypically heterogeneous condition, characterized microscopically by chromosomal instability and breakage. Affected individuals manifest growth restriction and congenital physical abnormalities; most progress to hematological disease including bone marrow aplasia. Black South African Fanconi anemia patients share a common causative founder mutation in the Fanconi G gene in 80% of cases (637_643delTACC-GCC). The aim of this study was to investigate the genotype-physical phenotype correlation in a cohort of individuals homozygous for this mutation.Methods: Thirty-five black patients were recruited from tertiary level hematology/oncology clinics in South Africa. Participants were subjected to a comprehensive clinical examination, documenting growth, congenital anomalies, and phenotypic variability.Results: Descriptive statistical analysis showed significant growth abnormalities in many patients and a high frequency (97%) of skin pigmentary anomalies. Subtle anomalies of the eyes, ears, and hands occurred frequently (≥70%). Apart from malformations of the kidney (in 37%) and gastrointestinal tract (in 8.5%), congenital anomalies of other systems including the cardiovascular and central nervous systems, genitalia, and vertebrae were infrequent (<5%). Conclusion:The diagnosis of Fanconi anemia in black South African patients before the onset of hematological symptoms remains a clinical challenge, with the physical phenotype unlikely to be recognized by those without dysmorphology expertise.Genet Med advance online publication 26 December 2013

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Fanconi anaemia (FA) is a genotypically and phenotypically heterogeneous genetic condition, characterized cytogenetically by chromosomal instability and breakage secondary to impaired DNA repair mechanisms. Affected individuals typically manifest growth restriction and congenital physical abnormalities and most progress to hematological disease including bone marrow aplasia. A rare genetic subtype of FA (FA-D1) is caused by biallelic mutations in the BRCA2 gene. Affected individuals manifest severe congenital anomalies and significant pigmentary changes and are additionally at risk for early onset leukemia and certain solid organ malignancies, including Wilms tumors and brain tumors. Parents of affected individuals are obligate carriers for heterozygous BRCA2 mutations and are thus potentially at risk for adult onset cancers which fall within the hereditary breast and ovarian cancer spectrum. We present two cases of black South African patients with FA diagnosed with biallelic BRCA2 mutations and discuss the phenotypic consequences and implications for them and their families. Recognition of this severe end of the phenotypic spectrum of FA is critical in allowing for confirmation of the diagnosis as well as cascade screening and appropriate care of family members.