MUS81 and Friedreich ataxia: Other components of the FA pathway, mutations of which are all associated with bona fide congenital FA, including BRCA2 and its binding partner FANCN, the FANCJ helicase (DOG-1 in C. elegans) as well as the XPF1 nuclease and the SLX4 multinuclease-scaffold protein (which provides a scaffold for XPF1, MUS81, and SLX1 nucleases), appear to function in downstream repair roles, as they are not required for the monoubiquitylation of FANCD2 and FANCI [for review, see Ceccaldi et al. (2016)].