In particular, the rare recessive form of optic neuropathy associated with mutations in the Transmembrane Protein 126A (TMEM126A) gene (OPA7), sometimes leading to additional neurological features (auditory neuropathy, sensorimotor axonal neuropathy, mild hypertrophic cardiomyopathy), was documented to lead to partial deficiency of complex I in one patient [54]. The gene discussed is TMEM126A; the disease is hypertrophic cardiomyopathy.