Bartter综合征二例家系报告与CLCNKB基因突变分析

Analysis of CLCNKB gene mutation in two families with Bartter syndrome

目的探讨儿童Bartter综合征的临床特点及CLCNKB基因突变分析。方法分析两个无血缘关系的Bartter综合征家系先证者及其家庭成员的临床资料,应用过柱法提取外周血DNA,针对Bartter综合征相关突变基因的外显子编码区设计引物、扩增,对PCR产物进行直接测序,与美国生物技术信息中心中的正常序列进行BLAST比对,从而发现可能存在的基因突变,最后多重连接探针扩增技术检测是否存在大片段缺失。结果两例家系的先证者检测均示:低钾血症、碱中毒、高肾素血症、高醛固酮血症。家系1先证者发现CLCNKB基因1~3、5~6、8、10~11、13~15、17~19号外显子大片段纯合缺失,分别遗传自父母;家系2先证者发现CLCNKB基因1~3、5~6、8、10~11、13~15、17~19号外显子大片段缺失与c.1881delC(p.Thr628fs)的复合杂合突变,分别遗传自父母。结论 c.1881delC(p.Thr628fs)为移码突变,该变异国内外尚未见报道。CLCNKB基因突变为2个Bartter综合征家系的致病原因,确诊为Ⅲ型Bartter综合征,临床分型属于经典型。临床上可通过分子遗传学技术进行Bartter综合征的基因诊断,提高确诊率,及时治疗。

Objective To explore the clinical characteristics of Bartter syndrome(BS) in children and analyze the characteristics of CLCNKB gene mutation. Methods The clinical data of two unrelated BS family probands and their family members were analyzed. The peripheral blood DNA was extracted with column method. Primers were designed for the coding region of exons of BS-related mutant genes and then amplified. The PCR products were sequenced and compared with the normal sequences in NCBI by BLAST to identify possible gene mutations. Large fragment deletions were detected with multiple ligation probe amplification technique. Results Laboratory tests of both probands showed hypokalemia, alkalosis, hyperreninemia and hyperaldosteroneemia. Large fragment homozygous deletions of exons 1-3, 5-6, 8, 10-11, 13-15 and 17-19 of CLCNKB were detected in pedigree 1, which were inherited from parents. Large fragment deletions of exons 1-3, 5-6, 8, 10-11, 13-15 and 17-19 of CLCNKB and c.1881 delC(p.Thr628 fs) compound heterozygous mutation were identified in pedigree 2, which were inherited from parents. Conclusion c.1881 delC(p.Thr628 fs) is a frameshift mutation, which has not been reported at home and abroad. CLCNKB gene mutation is the cause of the two BS families, and the diagnosis is type III classic BS. BS can be clinically identified with molecular genetics to improve the diagnosis rate and to implement timely treatment.