Combined Oxidative Phosphorylation Deficiency 21, is also known as combined oxidative phosphorylation defect type 21. An important gene associated with Combined Oxidative Phosphorylation Deficiency 21 is TARS2 (Threonyl-TRNA Synthetase 2, Mitochondrial). Affiliated tissues include globus pallidus and liver, and related phenotypes are seizure and global developmental delay