Mitochondrial Complex Iv Deficiency, Nuclear Type 11, also known as mc4dn11, is related to congenital nervous system abnormality and microcephaly. An important gene associated with Mitochondrial Complex Iv Deficiency, Nuclear Type 11 is COX20 (Cytochrome C Oxidase Assembly Factor COX20). Affiliated tissues include brain, and related phenotypes are ataxia and dysarthria