XRCC4 and Friedreich ataxia: These included genes encoding proteins involved in homologous recombination (HR)/Fanconi Anemia (FA) pathway (RAD51B, BRCA1, FANCD2, BRCA2), Non-Homologous end Joining (e.g. XRCC4) and mismatch repair (e.g. MSH2) (Figure 5A).