The mitochondrial tRNA^Lys (mt-tRNA^Lys) mutation is initially associated with myoclonic epilepsy and ragged-red fibers (MERRF). The clinical, laboratory, morphologic and molecular findings from 22 mt-tRNA^Lys mutation carriers from local database in East China were analyzed retrospectively. We identified 13 symptomatic and 9 asymptomatic individuals with a known pathogenic mitochondrial tRNA^Lys mutation. The most common mutations were m.8344 A>G (81.8%), m.8363G>A (9.1%), m.8356 T>C (4.5%) and m.8356 T>G (4.5%). The degree of mutation heteroplasmy in blood was high both in symptomatic (mean 64.5%, range 41–82%) and asymptomatic individuals (mean 53.1%, range 21–78%). Age at onset ranged from 6 year-old to the age of 66 years (mean 35.8 ± 16.4 years old). The most frequent symptoms were muscle weakness (76.9%), exercise intolerance (76.9%), elevated creatine kinase levels (61.5%), peripheral neuropathy (69.2%) and cerebellar ataxia (61.5%), while myoclonus was only present in 23.1% of symptomatic patients. A diagnosis of mitochondrial myopathy (MM) and neuropathy ataxia and retinitis pigmentosa (NARP/NARP-like) syndrome was made in 77% of symptomatic patients, whereas the classic syndrome of myoclonic epilepsy with ragged-red fibers (MERRF) was rare (23%). In this cohort of patients with mt-tRNA^Lys mutation, more than one third of our patients did not develop signs and symptoms of central nervous system involvement even in later stages of the disease, indicating the necessity to investigate the mt-tRNA^Lys gene in ‘pure’ mitochondrial ‘myo-neuropathy’.

线粒体tRNA ^Lys（mt-tRNA ^Lys）突变最初与肌阵挛性癫痫和衣衫red的红色纤维（MERRF）相关。回顾性分析了来自华东地方数据库的22个mt-tRNA ^Lys突变携带者的临床，实验室，形态和分子发现。我们确定了13例有症状的个体和9例无症状的个体，它们具有已知的致病性线粒体tRNA ^Lys突变。最常见的突变是m.8344 A> G（81.8％），m.8363G> A（9.1％），m.8356 T> C（4.5％）和m.8356 T> G（4.5％）。有症状的人（平均为64.5％，范围为41-82％）和无症状的人（平均为53.1％，范围为21-78％），血液中的异质突变程度都很高。发病年龄为6岁至66岁（平均35.8±16.4岁）。最常见的症状是肌肉无力（76.9％），运动耐量（76.9％），肌酸激酶水平升高（61.5％），周围神经病变（69.2％）和小脑共济失调（61.5％），而肌阵挛仅占23.1％有症状的患者。在77％有症状的患者中，诊断为线粒体肌病（MM）和神经病性共济失调和色素性视网膜炎（NARP / NARP-like）综合征，而带有参差不齐的红色纤维（MERRF）的典型的肌阵挛性癫痫综合征是罕见的（23％）。在这组mt-tRNA患者中^Lys突变，即使在疾病晚期，也有超过三分之一的患者未出现中枢神经系统受累的体征和症状，这表明有必要研究“纯”线粒体“肌神经病”中的mt-tRNA ^Lys基因。