Mutations in MT-TV which impair oxidate phosphorylation result in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). MELAS is a rare mitochondrial disorder known to affect many parts of the body, especially the nervous system and the brain. Symptoms of MELAS include recurrent severe headaches, muscle weakness (myopathy), hearing loss, stroke-like episodes with a loss of consciousness, seizures, and other problems affecting the nervous system. Two specific mutations of 1642G>A and 1644G>A have been found to result in the disease.[5]
Changes in the gene have also been associated with Leigh's syndrome, a progressive brain disorder characterized by vomiting, seizures, delayed development, muscle weakness, problems with movement, heart disease, kidney problems, and difficulty breathing. Symptoms typically appear in infancy or early childhood. A 1624C>T mutation has been linked to this disease.[6]
Other clinical manifestations associated with MT-TV mutations have included recurrent migraine headaches, muscle weakness and poor coordination, hearing loss, learning disabilities, dementia, and more. It has not been found why such mutations cause symptoms of these diseases.[5] A 1606A>G mutation resulted in ataxia accompanied by progressive seizures, mental deterioration, and hearing loss.[7] Cardiomyopathy, which weakens and enlarges the heart muscle, has also been reported in a small number of affected individuals.[5]
