SUCLA2 and mitochondrial DNA depletion syndrome: Nuclear-encoded genes associated with mtDNA depletion syndromes include genes important for mtDNA replication (POLG, TWINKLE), regulation of mitochondrial nucleotide pools (DGUOK, TP, TK2, RRM2B) and genes with poorly defined functions related to mtDNA maintenance, including, MPV17 and, interestingly, subunits of the Kreb’s cycle enzyme succinyl-CoA synthetase, SCS (SUCLG1, SUCLA2) (Suomalainen and Isohanni, 2010).