Mitochondrial encephalomyopathy: adolescent onset, recurrent hemiparesis, hemianopsia, convulsions, abdominal pain, headache and vomiting; ptosis and ocular fixation; easy fatigue and muscle aches after activity; early-onset familial diabetes mellitus, migraine, neurological deafness, hereditary optic neuropathy; chest tightness, palpitations, heart block and hypertrophic cardiomyopathy in adolescents.