NFU1 and Fatal multiple mitochondrial dysfunction syndrome type 2: Genetic defects in NFU1 (causing MMDS1, OMIM #605711), BOLA3 (causing MMDS2, OMIM #614299), and IBA57 (causing MMDS3, OMIM #615330), all factors acting in the final step of the assembly of [4Fe–4S] proteins, have been designated multiple mitochondrial dysfunction syndromes (MMDSs).