陳旧期で診断されたLeber視神経症の1例

A case of Leber optic neuropathy diagnosed at its late stage

15歳男性が両眼の視力と視野障害で紹介され受診した。6歳の時から視力の低下と回復を繰り返しながら次第に増悪し，視神経萎縮と診断されていた。受診時の矯正視力は右眼0.08，左眼0.4であった。両眼に視神経萎縮があり，蛍光眼底造影で乳頭と網膜血管の異常はなかった。両眼に中心暗点があった。病状の経過と検査所見からLeber視神経症が疑われ，承諾を得た上で遺伝子検査を行った。ミトコンドリアDNA11778番塩基対の点突然変異が検出され，Leber視神経症の診断が確定した。発症から長期間を経て診断された症例である。

A 15-year-old male was referred to us for poor vision and visual field in both eyes. His visual acuity had deteriorated after repeated episodes of impairment and recovery since the age of 6 years. He had been diagnosed with optic atrophy in both eyes. When seen by us,his corrected visual acuity was 0.08 right and 0.4 left. Both eyes showed optic atrophy. Fluorescein angiography gave inconclusive findings. The past history and clinical findings were suggestive of Leber hereditary optic atrophy. Genetic examinations were performed under informed consent. Mitochondrial analysis showed mutation in mtDNAl1778 and led to the diagnosis of the disease.