MT-ND5 and parathyroid gland adenoma: Regarding specific parathyroid adenoma subtypes, there is also an established correlation between oncocytic parathyroid adenomas and somatic mutations in genes encoded by mitochondrial DNA (mtDNA), especially mitochondrial respiratory chain complex genes NADH dehydrogenase 1, 4, and 5 (ND1, ND4, and ND5) (Table 1, Fig. 2).