Fanconi anemia is a rare autosomal recessive disease characterized by bone 
marrow failure, developmental anomalies, a high incidence of myelodysplasia and 
acute nonlymphocytic leukemia, and cellular hypersensitivity to cross linking 
agents. Five of the seven known Fanconi anemia proteins bind together in a 
complex and influence the function of a sixth, FANCD2, which colocalizes with 
BRCA1 in nuclear foci after genotoxic stress. Carboxy-terminal truncating 
mutations of the seventh Fanconi anemia gene, BRCA2, are hypomorphic and lead to 
FA-D1 and possibly FA-B. Because the Fanconi anemia alleles of BRCA2 fail to 
bind to Rad51 in response to genotoxic stress and Rad51 therefore fails to 
localize to nuclear damage foci, many investigators in the field suspect that 
the Fanconi anemia pathway supports the integrity of the Rad51 and BRCA1 and 
BRCA2 pathways as they function in homologous recombination repair. Because 
these abnormalities are common to all somatic cells, it is unlikely that 
dysfunction of this particular pathway results in tissue-specific apoptosis of 
hematopoietic cells. Indeed, at least one of the Fanconi anemia proteins, FANCC, 
exhibits functions in hematopoietic cells in addition to its role in the 
complex. Because FANCC protects hematopoietic cells from apoptotic cues in ways 
that do not require an intact heteromeric Fanconi anemia complex, it is 
reasonable to expect that the other Fanconi anemia gene products will have 
independent cytoplasmic and nuclear functions, particularly in hematopoietic and 
germ cells that seem to rely so substantially on an intact portfolio of Fanconi 
anemia proteins.