ID1 and Friedreich ataxia: In the classical FA pathway of ICL repair, ICL-blocked replication forks are first recognized by a FANCM‒FAAP24‒MHF1‒MHF2 protein complex, which in turn activates the FA core complex to mono-ubiquitinate FANCD2-I heterodimer (ID-Ub); this represents a key signaling step in the FA pathway [8,30,31].