Mutations in TMEM70, encoding a putative assembly factor of CV, were found in patients, mostly of Gipsy origin, with cardiomyopathy and isolated deficiency of ATP synthase [169]; the prevalent homozygous mutation, a A → G transition in intron 2 of the TMEM70 gene, results in aberrant splicing and loss of the mRNA transcript. This evidence concerns the gene TMEM70 and cardiomyopathy.