We analyzed data from 388 subjects with Fanconi anemia reported to the 
International Fanconi Anemia Registry (IFAR). Of those, 332 developed 
hematologic abnormalities at a median age of 7 years (range, birth to 31 years). 
Actuarial risk of developing hematopoietic abnormalities was 98% (95% confidence 
interval, 93% to 99%) by 40 years of age. Common hematologic abnormalities were 
thrombocytopenia and pancytopenia. These were often associated with decreased 
bone marrow (BM) cellularity (75% of cases studied). Clonal cytogenetic 
abnormalities developed in 23 of 68 persons with BM failure who had adequate 
studies. Actuarial risk of clonal cytogenetic abnormalities during BM failure 
was 67% (47% to 87%) by 30 years of age. Fifty-nine subjects developed 
myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML). Actuarial 
risk of MDS or AML was 52% (37% to 67%) by 40 years of age. Risk was higher in 
persons with than in those without a prior clonal cytogenetic abnormality (3% 
[0% to 9%] v 35% [0% to 79%]; P = .006). One hundred twenty persons died of 
hematologic causes including BM failure, MDS or AML and treatment related 
complications. Actuarial risk of death from hematologic causes was 81% (67% to 
90%) by 40 years of age.