網膜色素変性症と診断されていた進行例を含むX染色体若年網膜分離症の一家系

A pedigree of X-linked retinoschisis including a case simulating retinitis pigmentosa

　若年網膜分離症の典型的所見を有する3兄弟と，網膜色素変性症と診断されていた母方の祖父について報告した．

　祖父例は高度な視力・視野異常を有し，夜盲の自覚があり，眼底には不正形の色素斑が多数出現していた．さらに，周辺部網膜の樹枝状白色線や網膜から硝子体側へ隆起するu字状の半透明膜様物も認められた．後者の所見から原発性の網膜色素変性症は否定され，またGoldmann-Favre病は遺伝形式が異なる点で否定された．過去の報告例を検討した結果，祖父例は若年網膜分離症のsevere typeの進行例の特徴と一致しており，自験例の家系はX染色体劣性遺伝形式を示す若年網膜分離症であると結論された．X染色体若年網膜分離症の予後は比較的良好とされているが，一方では失明の報告もあり，自験例は本症の予後が老齢期においては必ずしも楽観できるものではない事を示す家系といえる．

We observed X-linked retinoschisis in 3 brothers aged 18, 25 and 28 years. Two cases manifested typ-ical fundus findings of foveal retinoschisis and the other manifested foveal and peripheral retinoschi-sis. Their grand father on the maternal side, aged 74 years, had been diagnosed as retinitis pigmentosa at the age of 47 years. Night blindness and constriction of visual field became more pronounced during the past 15 years. His visual acuity was now reduced to hand motion and finger counting each. Funduscopy showed diffuse retinochoroidal atrophy with pigment patches in addition to peripheral retino-schisis. The electroretinogram (ERG) was almost extinguished. Because of these findings, retinitis pigmentosa and Goldmann-Favre disease were ruled out, suggesting severe and advanced X-linked retinoschisis as the most probable diagnosis.From the clinical features of this pedigree, it is concluded that X-linked retinoschisis may simulate retinitis pigmentosa particularly in aged subjects of severe type.