目的 报告1例儿童期发病亨廷顿病（COHD）患儿的临床特征及遗传改变，探讨改良高通量测序数据分析方法检出CAG重复扩增变异的可能。方法 经外显子组测序（ES）STR分析（ES-STR）发现1例COHD病例，回顾性分析该患儿的临床资料，总结COHD的遗传学和表型特征。结合大规模临床ES数据，分析基于ES数据对HTT(CAG)n扩增的检测效果。结果 先证者，男，16岁，主要临床表现为言语发育迟缓、运动倒退、行走不稳。通过分析ES结果发现患儿Huntington（HTT）基因上(CAG)n重复拷贝数为83/17，家系验证结果发现患儿父亲HTT基因上(CAG)n重复拷贝数分别为44/18。文献检索共纳入15篇文献，共20例患儿，临床表现主要以言语迟缓、运动障碍、肌张力障碍为主，平均发病年龄（4.23±2.33）岁，(CAG)n 重复拷贝数范围为51~312次。ES在HTT(CAG)n位点覆盖较好，可以有效的将CAG重复数超过病理阈值的病例检测出来，但是随着CAG重复数目增加，检测出的CAG数目和实际出现偏差，还需依赖验证时得出准确的重复数。结论 ES-STR对于亨廷顿舞蹈症是一种有效的诊断方法，特别对于临床表型不典型的COHD患儿，在高通量测序方法中即可有效分析诊断，本文通过归纳COHD患儿的临床表现，以助于临床诊断，避免误诊、漏诊发生。

Objective To report the clinic characteristic and genetic variant of a patient with childhood-onset Huntington disease (COHD), investigate the possibility of enhanced next-generation sequencing data to detect CAG repeat expansion and increase the outstanding of the disease through literature review. Method A COHD case was identified by exome sequencing combined with STR analysis (ES-STR), and the genetic and clinical date of the COHD patient were analyzed. Results The proband, a 16-year-old boy, presented with speech delay, hypokinesia and unsteady walking. ES analysis revealed 83 CAG repeats in Huntington gene (HTT) inherited from his father with 44 CAG repeats in HTT. In total, 15 articles and 20 patients related to COHD were included in literature review. Speech delay, dyskinesia, dystonia were major manifestations. The average onset was (4.23±2.33) years and the range of CAG repeat number of HTT gene was 51-312. ES demonstrated adequate coverage in the HTT locus and could identified cases with pathogenic expansion while large expansion needs additional validation to determine the precise repeat length. Conclusion The patient with COHD tended to have speech delay and movement disorder as the initial symptom instead of involuntary choreiform movements. ES-STR is an efficient diagnosis for Huntington disease (HD), particularly in COHD exhibiting non-classical phenotype. This article summarized the clinical features of COHD to improve the diagnosis for this rare disease and avoid undiagnosis and misdiagnosis.