RAD51 and Friedreich ataxia: Replication fork instability is a cellular phenotype of FA/BRCA pathway deficient cells mainly studied in FA subgroups with known replication fork-associated functions (FANCD1/BRCA1, FANCF/RAD51, FANCS/BRCA2, FANCU/XRCC2, FANCO/RAD51C and FANCN/PALB2) that are classical HR factors which act in the downstream part of the FA/BRCA pathway [39].