42例3型巴特综合征CLCNKB基因变异分析和基因型/表型研究

目的分析中国42例3型巴特综合征(Bartter syndrome type 3,BS3)患儿的CLCNKB基因变异,探讨基因型与临床表型的特点。方法42例经基因检测确诊的BS3病例来自2012年6月至2018年10月青岛大学附属医院和青岛大学附属市立医院收治的患儿,分别来自40个汉族家系和1个回族家系。采用二代测序和多重连接酶探针依赖扩增(MLPA)技术分析BS3患儿的CLCNKB基因变异及其特点。收集患儿临床资料,观察和随访药物治疗疗效和生长发育改善的情况。根据基因变异的严重程度将患儿分为2组:严重变异基因型组(严重变异组,n=26)和轻度变异基因型组(轻度变异组,n=12)。比较两组患儿的临床表型特征。结果42例BS3患儿的二代测序和MLPA分析共确定CLCNKB基因36个变异,其中16个为新发现变异。CLCNKB基因大片段缺失频率高达55%,全基因缺失达40%,全基因缺失是最常见的基因突变类型。患儿最常见的临床表现为生长迟缓(38/42)、多饮多尿(35/42)、便秘(31/42)和呕吐(27/42)。42例患儿均表现为低钾低氯代谢性碱中毒。经氯化钾和吲哚美辛为基础的药物治疗后,大部分患儿的生长发育和电解质紊乱得到明显改善。与轻度变异组相比,严重变异组表现出更严重的代谢性碱中毒。结论本研究发现CLCNKB基因36个变异,其中16个为新变异,丰富了人类基因突变库,为BS3的诊治以及中国巴特综合征人群遗传咨询的开展提供了有益的借鉴。

Variant analysis and genotype/phenotype association study in 42 Chinese patients with Bartter syndrome type 3

Objective To analyze the variants of 42 Chinese patients with Bartter syndrome type 3 (BS3) and explore the characteristics of genotype and phenotype. Methods Forty-two genetically diagnosed patients from 40 Han and one Hui families were collected in the Affiliated Hospital of Qingdao University and the Affiliated Qingdao Municipal Hospital of Qingdao University during the period of June 2012 to October 2018. The second-generation sequencing and multiplex ligase probe-dependent amplification (MLPA) technique were used to analyze the CLCNKB gene variation and its characteristics in children with BS3. The clinical data were collected, and the therapeutic effect and growth improvement were observed and followed up. Thirty eight patients were divided into severe (n=26) and light (n=12) groups according to the severity of genetic variation. The clinical phenotypic characteristics of the two groups were compared. Results Thirty-six variants including 16 novel ones of CLCNKB gene were found. The whole gene deletion of CLCNKB gene was the most frequent mutation (40%), and the rate of large deletions was up to 55%. The most common symptoms included development retardation (38/42), polydipsia and polyuria (35/42), constipation (31/42) and vomiting (27/42). All patients presented with hypokalemia, hypochloremia and metabolic alkalosis. After the medicine treatment that based on indomethacin and potassium chloride, most patients could achieve obvious recovery of growth rate and restoration of hypokalemia. The severe group showed more severe metabolic alkalosis than the light group. Conclusions Thirty-six variants of CLCNKB gene have been found in this study, including 16 novel ones, which enrich the human gene mutation database (HGMD) and provide valuable references to diagnosis, treatment and the genetic counseling of Chinese population.