Recessive TWNK mutations are causative for mitochondrial DNA depletion syndrome 7 (MTDPS7; OMIM #271245) also known as infantile-onset spinocerebellar ataxia (IOSCA) [49, 50] and were recently identified in patients with PRLTS5 [6, 10] (Table 3). This evidence concerns the gene TWNK and mitochondrial DNA depletion syndrome 7 (hepatocerebral type).