SYNE1基因突变致常染色体隐性遗传小脑共济失调1型表型分析

Clinical phenotypes study of autosomal recessive cerebellar ataxia type 1 caused by SYNE 1 gene mutations

目的探讨常染色体隐性遗传小脑共济失调1型(autosomal recessive cerebellar ataxia type1,ARCA1)家系患者的临床特征及致病基因SYNE1的突变特点。方法应用全外显子组测序技术对中日友好医院运动障碍与神经遗传病研究中心2005—2018年收集的80个已排除Friedreich共济失调的拟诊常染色体隐性遗传共济失调家系先证者进行基因检测,结合Sanger测序对先证者及家系成员进行致病突变验证,并详细分析所有患者的临床表型。结果检测发现3个SYNE1基因突变导致的ARCA1家系。家系1先证者携带纯合移码突变c.12670dupC(p.L4224fs),表现为纯小脑萎缩性共济失调症状。家系2先证者携带复合杂合突变c.20826+1G>T和c.25954C>T(p.R8652X),表现为小脑萎缩性共济失调伴上运动神经元损害。家系3先证者和大哥均携带复合杂合突变c.21955C>T(p.Q7319X)和c.23777C>A(p.T7926K),表现为精神行为异常及认知障碍、小脑萎缩性共济失调和上运动神经元损害的多系统病变。4例患者头颅MRI均提示小脑明显萎缩,家系3先证者额颞叶也有轻度萎缩。结论SYNE1基因突变导致的ARCA1表现为小脑性共济失调,并可伴有运动神经元损害和认知功能障碍。ARCA1在中国人群罕见且临床表型复杂,高通量测序技术有助于快速诊断该病,并进一步扩展基因型与表型的相关性。

Objective To investigate the clinical features of autosomal recessive cerebellar ataxia type 1 (ARCA1) and analyze the pathogenic variants in SYNE 1 gene. Methods A cohort of 80 probands of autosomal recessive cerebellar ataxia pedigrees excluding Friedreich ataxia were detected by whole-exome sequencing technology. Potential pathogenic variants were confirmed by Sanger sequencing. Clinical phenotypes of positive patients were analyzed in detail. Results Three pedigrees of ARCA1 caused by SYNE 1 gene variants were found. The proband of pedigree 1 carried homozygous frameshift mutation c.12670dupC(p.L4224fs), presented as pure cerebellar ataxia. The proband of pedigree 2 carried compound heterozygous mutations c.20826+1G>T and c.25954C>T(p.R8652X), presented as cerebellar ataxia plus upper motor neuron dysfunction. The proband of pedigree 3 carried compound heterozygous mutations c.21955C>T(p.Q7319X) and c.23777C>A(p.T7926K), presented as mental behavior and cognitive impairment, cerebellar ataxia and upper motor neuron dysfunction. Brain MRI showed obvious cerebellar atrophy in all patients, and the fronto-temporal lobes were also found slight atrophy in proband of pedigree 3. Conclusions The phenotype of ARCA1 caused by SYNE 1 gene mutations is characterized by cerebellar ataxia, maybe accompanied with motor neuron damage and cognitive dysfunction. ARCA1 is a rare form of autosomal recessive cerebellar ataxia in Chinese population, with a complex phenotype. The use of next generation sequencing allows the rapid analysis of ARCA1, and will likely further expand genotype-phenotype correlations.