Homozygous and compound heterozygous pathogenic variants in PTCD3 cause the combined oxidative phosphorylation deficiency 51 (COXPD51), for which symptoms include respiratory insufficiency, nystagmus, delayed psychomotor development, brain lesions, bilateral hearing loss, and optic atrophy (OMIM #619057) [30]. The gene discussed is PTCD3; the disease is optic atrophy.