Fatal infantile mitochondrial encephalomyopathy, hypertrophic cardiomyopathy, and optic atrophy are associated with a homozygous gene mutation in OPA1, which results in a marked loss of steady-state levels of the native OPA1 protein, with a mitochondrial morphology consistent with abnormal mitochondrial membrane fusion [91]. The gene discussed is OPA1; the disease is optic atrophy.