MSH2 and Friedreich ataxia: To further illustrate the complexity of the FA pathway, depletion of the mismatch repair protein MSH2 rescued MMC-hypersensitivity in cells defective for FANCJ (FA group 3) and FANCD2 (FA group 2), but not FANCA (FA group 1); thus, separating FA group 1 from groups 2 and 3 (59).