Septo‐optic dysplasia associated with a new mitochondrial cytochrome b mutation

Abstract
We report on a 25‐year‐old patient with isolated mitochondrial complex III deficiency and a new heteroplasmic mutation (T14849C) in the cytochrome b gene. He suffered from septo‐optic dysplasia, retinitis pigmentosa, exercise intolerance, hypertrophic cardiomyopathy, and rhabdomyolysis. A HESX1 mutation was excluded as a cause of his septo‐optic dysplasia. Low α‐tocopherol concentrations in his muscles and an elevated urinary leukotriene E4 excretion indicate increased production of reactive oxygen species.