Mitochondrial Complex Iv Deficiency, Nuclear Type 6, is also known as cardioencephalomyopathy, fatal infantile, due to cytochrome c oxidase deficiency 2. An important gene associated with Mitochondrial Complex Iv Deficiency, Nuclear Type 6 is COX15 (Cytochrome C Oxidase Assembly Homolog COX15). Affiliated tissues include brain, and related phenotypes are hypotonia and retinopathy