原発性定型網膜色素変性の遺伝的異質性と予後に関する18施設調査

Genetic heterogeneity and visual outcome in typical retinitis pigmentosa:A collaborative study of eighteen institutions

　1990年の6か月間に18施設を受診した定型網膜色素変性534例（男性252例，女性282例）の遺伝形式別頻度は孤発例（孤発）54％，常染色体劣性（劣性）25％，常染色体優性（優性）17％，X染色体性（X性）2％，推定困難が2％であった。自覚症状発現時期は平均26歳で，X性が最も早く，優性と劣性の間に有意差は認められなかった。視力0.1以下の眼は，20歳未満で10％，20〜39歳で25％，40〜59歳で38％と上昇し，60歳以上で43％であり，経過年数20年未満では21％で，20〜39年で43％，40〜59年で61％と上昇し，60年以上で67％であった。高度視野障害眼の頻度は視力0.1以下の眼の頻度を上まわっていた。優性と孤発は劣性よりも障害が軽い傾向が認められた。遺伝形式別頻度や，高度障害の年齢や経過年数別頻度，ならびに遺伝形式による予後の差異は，遺伝相談および経過の説明に際し，有用な資料となり得る。

We reviewed 534 patients with typical retinitis pigmentosa seen during a 6-month period in 1990. Eighteen institutions throughout Japan participat-ed in study. The series comprised 252 males and 282 females. The incidence of genetic types was 54% simplex, 25% autosomal recessive, 17% autosomal dominant, 2% X -linked and undetermined in 2%. Subjective symptoms became manifest at the aver-age age of 26 years. Its onset was significantlyearlier in X -linked type than in others. There was no difference in the age of onset between autosomal recessive and dominant types. The prevalence of eyes with visual acuity of 0.1 or less was 10% below 20 years of age, 25% for 3rd and 4th decades, 38% for 5 th and 6 th decades, and 43% for 7 th and 8 th decades. It was 21% when the duration of the disease was 20 years or less, and 43%, 61% and 67% for each conssecutive 20-year duration group. Advanced constriction of visual field was more common than poor visual acuity of 0.1 or less. Loss of visual acuity was milder in autosomal dominant and simplex types than autosomal recessive one. These results will be useful for the genetic and clinical counselling for patients with retinitis pig-mentosa.