IBA57 and Encephalopathy: Biallelic mutations in IBA57, encoding a Fe/S mitochondrial protein assembly factor, can be responsible for a slowly progressive childhood-onset HSP (Lossos et al. 2015), up to multiple mitochondrial dysfunction syndrome 3 (MMDS3; OMIM #615330), a severe lethal encephalopathy with multiple malformations, myopathy and hyperglycinemia (Ajit Bolar et al. 2013).