FANCD2 and Friedreich ataxia: Indeed, cells with specific patient mutations in either BRCA2/FANCD1 or RAD51/FANCR are defective in replication fork protection but remain proficient for HDR9,10, and restoration of fork protection without restoration of interstrand crosslink repair functions can reestablish hematopoietic stem cell functions in Fancd2-/- mice11, suggesting physiological importance of this distinct molecular pathway in FA disease.