That the FAN1 gene has not been found to be mutated in Fanconi anemia (FA) patients is most likely due to its functional redundancy with other nucleases in the pathway, such as SLX1 and/or SNM1A, neither of which is, like FAN1, encoded by an FA gene (see reference 25 for a recent review). Here, FAN1 is linked to Friedreich ataxia.