MT-CYB and Huntington disease: A study performed in leukocytes found increased levels of the DNA oxidation product OH8dG and of deleted and total mitochondrial DNA (mtDNA) copy numbers in patients with HD, while mRNA expression levels of mtDNA-encoded mitochondrial enzymes, and expression levels of NADH dehydrogenase subunit 1 (ND1), cytochrome b (CYTB), and cytochrome c oxidase I (COXI) were similar to those of HC patients [28].