網膜変性を伴ったmitochondrial cytopathy（cytochrome C oxidase部分欠損症）の双生児例

Identical twins with mitochondrial cytopathy and retinal degeneration

　筋生検にてcytochrome C oxidaseの部分欠損が証明されたmitochondrial cytopathyの一卵性双生児7歳例を経験した。

　本例の1例は幼児期に，網膜変性を認めた。眼底精査を行った今回の時点で両児とも，網膜の色素上皮の萎縮，視神経乳頭の蒼白化を認め，同時に行ったERGでは振幅は低下していた。過去の本症に認められた眼所見とは，発症時期および眼瞼下垂，眼球運動障害がないという点で異なっていた。

　本例は眼所見，および発達の遅れ，代謝異常という全身所見が同様であることより先天的な遺伝子障害が考えられ，本症の遺伝形式を考えるうえでも意義があると考えた。

A pair of identical male twins, aged 7 years, presented with diffuse retinal degeneration in both eyes. The retina showed fine sprinkling pigments and white spots. Optic atrophy was present. Electroretinogram was subnormal. There were no disturbance of eye movement or ptosis. Retinaldegeneration had been detected in one of the twins at the age of 3 years. Biopsy of brachial biceps muscle showed partial deficiency of cytochrome C oxydase and led to the diagnosis of mitochondrial cytopathy. This is the first report on association of early-onset retinal degeneration and mitochondrial cytopathy. Because of similarity of fundus findings in both twins, congenital gene mutation may have been involved in its etiology.