USP1 and Friedreich ataxia: USP1-mediated deubiquitination of FANCD2 and FANCI is crucial for the correct function of the FA pathway, as evidenced by the observation that USP1 gene knockout in murine models or DT40 chicken cells recapitulates many phenotypical aspects of FA, including haematopoietic defects and hypersensitivity to DNA crosslinking agents [61-64].