Functional confirmation of Gitelman's syndrome mutations in Japanese
Functional confirmation of Gitelman's syndrome mutations in Japanese
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DOI：
10.1291/hypres.28.805
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发表时间：
2005-10-01
影响因子：
5.4
通讯作者：
Iwai, N
中科院分区：
文献类型：
--
作者：
Naraba, H;Kokubo, Y;Iwai, N
Gitelman综合征是一种常染色体隐性遗传性肾小管疾病，由噻嗪敏感性氯化钠协同转运蛋白基因（SLC 12 A3）的功能缺失突变引起。我们以前曾报道，报告的Gitelman综合征突变的组合等位基因频率为0.0321。然而，几乎所有报告的Gitelman综合征突变都来自病例报告，没有功能确认。在本研究中，我们使用哺乳动物细胞表达系统评估了日本人T180 K和L 849 H两种最常见突变的功能。人SLC 12 A3 cDNA在巨细胞病毒（CMV）启动子控制下在中国仓鼠卵巢（CHO）细胞中瞬时表达。通过定点诱变引入T180 K和L 849 H突变。通过测量示踪剂Na-22（+）摄取来评估Na+-Cl-协同转运蛋白的活性。虽然T180 K变异只是一种多态性，但L 849 H突变被证实是一种功能缺失突变，似乎与Gitelman综合征有关。这一观察结果可能具有非常重要的临床意义，因为这种变异的等位基因频率为0.0126。
Gitelman's syndrome is an autosomal recessive inherited renal tubular disorder resulting from loss-of-function mutations in the thiazide-sensitive sodium chloride cotransporter gene (SLC12A3). We have previously reported that the combined allele frequency for the reported Gitelman's syndrome mutations is 0.0321. However, almost all of the reported Gitelman's syndrome mutations were from case reports without functional confirmation. In the present study, we assessed the functionality of the two most prevalent mutations in Japanese, T180K and L849H, using a mammalian cell expression system. Human SLC12A3 cDNA was transiently expressed in Chinese hamster ovary (CHO) cells under the control of a cytomegalo virus (CMV) promoter. The T180K and L849H mutations were introduced by site-directed mutagenesis. The activity of the Na+-Cl- cotransporter was assessed by measuring tracer Na-22(+) uptake. While the T180K variation was just a polymorphism, the L849H mutation was confirmed to be a loss-of-function mutation and appears to be responsible for the Gitelman's syndrome. This observation may have very important clinical implications, since the allele frequency of this variation is 0.0126.