COA6 and cardiomyopathy: Notably, two mitochondrial transcripts, cytochrome C oxidase assembly factor 6 (COA6) [48] and NADH:ubiquinone oxidoreductase complex assembly factor 2 (NDUFAF2 [49]), had lower levels in patients compared with controls, which is consistent with previous reports linking their deficiency or absence to cardiomyopathies.