MTRFR and peripheral neuropathy: When MTRFR is deficient or mutated, mitochondrial translation remains stalled, leading to a severe and disabling neurological disease with spastic paraparesis, optic and peripheral neuropathy diagnosed as Behr's syndrome (Buchert et al., 2013; Pyle et al., 2014; Shimazaki et al., 2012; Spiegel et al., 2014), Leigh syndrome (Heidary et al., 2014) and CMT6 (Tucci et al., 2014).