男性先天赤緑色覚異常者における遺伝子診断の有用性

Value of genetic testing in males with X-linked red/green color vision deficiencies

要約　目的：男性先天赤緑色覚異常者における遺伝子診断についての検討。対象と方法：26例に対し，アノマロスコープによる診断に加え，パネルD-15を用いてpassを軽度異常，failを強度異常とする程度判定を行った。L・M視物質遺伝子配列をpolymerase chain reaction法で決定し，上流（5'端）の2つの遺伝子から想定される視物質の分光吸収極大波長の差を波長差として求めた。結果：1型色覚異常が11例，2型色覚異常が15例であった。異常3色覚者の85％（11/13例）で波長差が検出され，2色覚の13例全例で波長差は検出されなかった。軽度異常と強度異常を分類するための特徴的な遺伝子配列は見出せなかった。結論：遺伝子診断法は異常3色覚と2色覚の鑑別に有用と考えられた。

Abstract.　Purpose：To report the value of genetic testing in X-linked red/green color deficiencies in males. Cases and Method：This study was made on 26 males. They were diagnosed either as dichromat or anomalous trichromat by Nagel model I anomaloscope. Severity of color vision defect was determined either as pass or fail by Farnsworth panel D-15 test. Genotypes of L and M visual pigment were determined by polymerase chain reaction. Calculation was made regarding difference in absorption maxima between the first two visual pigment genes. Results：Out of 26 cases, 11 were diagnosed as protan and 15 as deutan. All the 13 dichromats showed no difference in absorption maxima. Out of 13 cases with anomalous trichromacy, 11（85％）showed some separation in absorption maxima. No distinctive genotypes were found that distinguish severe（dicromacy and severe anomalous trichromacy）from mild（mild anomalous trichromacy）forms. Conclusion：Genetic testing promises to be of value in disgtinguishing dichromacy from anomalous trichromacy.