线粒体呼吸链复合物Ⅲ缺陷五例的临床特点与生化分析

Enzyme analysis of isolated mitochondrial respiratory chain complex III deficiency

目的对5例线粒体呼吸链复合物Ⅲ缺陷患儿进行临床特点和生化分析。方法对5例患儿（男3例，女2例）临床特点进行归纳总结，并抽取患儿静脉血，分取白细胞线粒体蛋白，采用分光光度测定法检测线粒体呼吸链复合物Ⅰ—Ⅴ活性。结果（1）5例分别于1个月～15岁时来院就诊。其中3例临床表型符合Leigh综合征，主要表现为智力运动发育落后，运动倒退。1例表现为肝损害，胆汁淤积症。1例表现为进行性肌无力。（2）线粒体呼吸链复合物Ⅰ＋Ⅲ活性为3．0～14．2nmoL／（min·mg线粒体总蛋白），200名正常对照为84．4±28．5nmol／（min·mg线粒体总蛋白），患儿酶活性降低至正常对照的10．4％-49．3％；复合物Ⅰ＋Ⅲ与柠檬酸合酶活性比值为3．5％～22．9％，显著低于正常对照[（66．1±14．7）％]，复合物Ⅰ、Ⅱ、Ⅳ和V活性正常，符合单纯线粒体呼吸链复合物Ⅲ缺陷诊断。结论线粒体呼吸链复合物Ⅲ缺陷病临床表现复杂多样，累及多个系统；复合物Ⅰ＋Ⅲ活性以及与柠檬酸合酶活性比值均低于正常对照，而所有患儿复合物Ⅰ、Ⅱ、Ⅳ和∨活性均未发现异常。

Objective To study the clinical and enzymological characteristics of the children with mitochondrial respiratory chain complex Ill deficiency. Method The clinical manifestations of five patients （3 males, 2 females） were summarized. Spectrophotometric assay was used for the analysis of respiratory chain complex I to V enzyme activity in peripheral blood leukocytes, after obtaining venous blood. Result （ 1 ） Five patients were hospitalized at the age of 1 month to 15 years. Three patients had Leigh syndrome with progressive motor developmental delay or regression and weakness. One had severe liver damage and intrahepatic cholestasis. One presented muscle weakness. （2） Deficient complex Ⅰ ＋ Ⅲ activity was identified in five patients. Their complex Ⅰ ＋ Ⅲ activities in peripheral blood leukocytes were 3.0 to 14. 2 nmol/min per mg mitochondrial protein （control： 84. 4 ± 28.5 nmol/min per mg mitochondrial protein）. The ratio of complex Ⅰ ＋ Ⅲ to citrate synthase decreased to 3.5 to 22.9% （ normal control 66. 1 ± 14. 7 % ）. The activities of complex Ⅲ decreased to 10.4 to 49.3% of the lowest control value,while complex Ⅰ , Ⅱ , Ⅳ and V activities were normal. The results supported the diagnosis of isolated respiratory chain complex Ⅲ deficiency. Conclusion Complex m deficiency is a kind of disorder of energy metabolism with various manifestations. The complex Ⅰ ＋ Ⅲ activities and the ratio of complex Ⅰ ＋ Ⅲ to citrate synthase were lower than those of the control. The activities of complex Ⅰ. Ⅱ . IV and Ⅴ were normal.