该突变可导致原有的限制性内切酶saNI的切点消失,正常人 mtdNA 经sNI酶切后产生915bp、679bp两个片段,而LHON患者 mtDNA 经酶切后只产生1590bp片段。 Leber's hereditary optic neuropathy LHON 1. HON has been linked to point mutations in the mtDNA 2. LHON is expressed predominantly in males of the lineage unexplained 3.The onset of visual loss typically occurs between the age of 15 and 35 years 4. Visual loss is painless, central, and occurs in one eye week to months before second eye involvement. On rare occasions, the disease may remain clinically monocular 线粒体脑肌病 线粒体脑肌病( mitochondrial encephalomyopathies,ME)是一组 由于线粒体功能缺陷引起的多系统疾病,以中枢神经和肌肉系统病变 为主,特征是呼吸链酶活性正常的肌纤维与酶活性缺失的肌纤维混 合。患者各种组织内 mtDNA的突变类型、分布各不相同,所以表现 出不同的症状,多表现为肌力低下、易疲劳、小脑失调、耳聋、痴呆、 代偿性高乳酸血症等。根据临床表现,将线粒体脑肌病分为:伴有破 碎红纤维的肌阵挛癫痫( myoclonic epilepsy and ragged red fibers, MERRF)、线粒体脑肌病合并乳酸血症及卒中样发作( mitochondrial encephalomyopathy with lactic acidosis, and stroke-like episodes MELAS, Kearns-Sayre综合征(KSS)、慢性进行性眼外肌瘫痪( chronic progressive external ophthalmoplegia,CPEO)、神经源性肌软弱、共济 失调并发色素性视网膜炎( neurogenic muscle weakness; ataxia,and6 该突变可导致原有的限制性内切酶sfaNⅠ的切点消失，正常人mtDNA 经 sfaNⅠ酶切后产生 915bp、679bp 两个片段，而 LHON 患者 mtDNA 经酶切后只产生 1590bp 片段。 Leber’s hereditary optic neuropathy(LHON) 1.LHON has been linked to point mutations in the mtDNA. 2.LHON is expressed predominantly in males of the lineage ≥ unexplained. 3.The onset of visual loss typically occurs between the age of 15 and 35 years. 4.Visual loss is painless, central, and occurs in one eye week to months before second eye involvement. On rare occasions, the disease may remain clinically monocular. 二、线粒体脑肌病 线粒体脑肌病（mitochondria1 encephalomyopathies，ME）是一组 由于线粒体功能缺陷引起的多系统疾病，以中枢神经和肌肉系统病变 为主，特征是呼吸链酶活性正常的肌纤维与酶活性缺失的肌纤维混 合。患者各种组织内 mtDNA 的突变类型、分布各不相同，所以表现 出不同的症状，多表现为肌力低下、易疲劳、小脑失调、耳聋、痴呆、 代偿性高乳酸血症等。根据临床表现，将线粒体脑肌病分为：伴有破 碎红纤维的肌阵挛癫痫（myoclonic epilepsy and ragged red fibers， MERRF）、线粒体脑肌病合并乳酸血症及卒中样发作(mitochondrial encephalomyopathy with lactic acidosis，and stroke-like episodes， MELAS)，Kearns-Sayre 综合征（KSS）、慢性进行性眼外肌瘫痪（chronic progressive external ophthalmoplegia，CPEO）、神经源性肌软弱、共济 失调并发色素性视网膜炎（neurogenic muscle weakness,ataxia,and