UQCRC2 and obstructive sleep apnea syndrome: The expression levels of a subunit of nicotinamide-adenine dinucleotide dehydrogenase (complex I; NDUFB8), a subunit of succinate dehydrogenase (complex II; SDHB), ubiquinol–cytochrome c reductase complex (complex III; UQCRC2), subunit I of cytochrome c oxidase (complex IV; MTCO1), and the α subunit of F0F1-ATP synthase (complex V; ATP5A) were higher in the OSA group than in the Sham group (P < 0.05).