Huntington舞蹈病一家系4例遗传分析

目的对Huntington舞蹈病一家系4例进行遗传学分析,为家系成员提供遗传咨询并为后续Huntington舞蹈病发病机制及实验治疗研究提供依据。方法对患者家系进行家系调查和分析,观察患者症状,对患者进行医院常规检查及实验室遗传学分析。结果通过基因诊断,家系中有7人携带Huntington舞蹈病基因。其中2人表现为Huntington舞蹈病典型不自主震颤;2人具有高度区域选择性的脑萎缩和神经元脱失;3人表型正常,未到发病年龄,表现为延迟显性。结论 Huntington舞蹈病是一种以神经系统退行性改变为主要特征的常染色体显性遗传病,发病年龄通常在32～50岁。其遗传学基础是由于基因的动态突变———IT15基因5′端编码区(CAG)n三核苷酸的异常扩增引起的,呈现典型的延迟显性和遗传印记现象。

Genetic analysis on four cases of a family with Huntington disease

Objective To analyze genetically a family with Huntington disease and provide family members with genetic counseling and prepare for the further research on pathogenesis and experimental therapy of Huntington disease.Methods The family of patients with Huntington disease were investigated and analyzed;Hospital routine inspection,genetics laboratory analysis and symptoms observation were carried out on the patients.Results Gene diagnosis showed that totally 7 family patients suffering from Huntington disease.Two patients had typical uncontrollable tremors;two patients were eager for a highly selective area of the brain shrinkage and neuron loss;three patients before the age of onset retained normal phenotype and manifested delayed dominance.Conclusion Huntington disease is an autosomal dominant disorder characteristic of selective neurodegeneration caused by an expansion of CAG triplet repeats within coding region of the IT15 gene,and has a dominant characteristic of delayed dominanace and genetic imprinting phenomenon.Huntington disease can occur at any age,but in most cases,the age at onset ranges from 32 to 50 years old.