However, the mitochondrial genes harboring synonymous variants were only positively associated with the risk of obesity, such as cytochrome c oxidase III (MT-CO3), nicotinamide adenine dinucleotide (NADH) dehydrogenase 2 (MT-ND2), NADH dehydrogenase 4 (MT-ND4), NADH-ubiquinone oxidoreductase chain 4L (MT-ND4L), and non-coding variants; as well as tRNA histidine (MT-TH), tRNA serine 1 (MT-TS1), and tRNA phenylalanine (MT-TF). Here, MT-ND4 is linked to obesity due to melanocortin 4 receptor deficiency.