Clinical and genetic studies of CLCN5 mutations in Japanese families with Dent's disease
Clinical and genetic studies of CLCN5 mutations in Japanese families with Dent's disease
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DOI：
10.1046/j.1523-1755.2000.00198.x
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发表时间：
2000-08-01
影响因子：
19.6
通讯作者：
Thakker, RV
中科院分区：
文献类型：
--
作者：
Igarashi, T;Inatomi, J;Thakker, RV
背景登特氏病是一种X染色体连锁的肾小管疾病，其特征是低分子量蛋白尿。高钙尿症、肾结石和肾衰竭。这种疾病是由肾氯离子通道基因CLCN 5失活引起的。其编码具有12至13个跨膜结构域的746个氨基酸的蛋白质。据观察，登特氏病的日本变种不那么严重。我们已经调查了两个不相关的日本家庭的CLCN 5突变。来自两个无关家庭的六名患者进行了研究。先证者的白细胞DNA与CLCN 5特异性引物一起用于聚合酶链反应（PCR）扩增编码区和外显子-内含子边界，并确定产物的DNA序列以识别基因异常。从肾脏、白细胞或尿沉淀物中提取的RNA用于进一步表征所鉴定的突变的影响。在5名患者中检测到β（2）-微球蛋白尿，在2名患者中检测到高钙尿，在3名患者中检测到肾结石（其中2名是女性），并且1名51岁男性患有肾衰竭。两个新的CLCN 5突变组成的，在内含子5的不变的ag受体剪接位点的a到g的转换和基因内缺失，包括内含子3和内含子6之间的区域进行了鉴定。受体剪接位点突变导致利用外显子6中的两个选择性隐蔽剪接位点，这导致外显子6的移码或跳跃。缺失突变。这导致外显子II、5和6的丢失。预计会导致结构域1至4的损失。这两种突变都预测了可能导致功能丧失的截短氯离子通道。一名男性肾衰竭和两名女性肾结石的观察结果代表了与CLCN 5突变相关的日本Dent病变体的重要新发现。此外，我们的研究是第一个证明使用尿沉渣细胞和肾组织检测CLCN 5转录异常。这些结果有助于扩大与登特病相关的CLCN 5突变谱。
Background. Dent's disease is an X-linked renal tubular disorder that is characterized by low molecular weight protein-uria. hypercalciuria, nephrolithiasis, and renal failure. The disease is caused by inactivation of a renal chloride channel gene, CLCN5. that encodes a 746-amino acid protein with 12 to 13 transmembrane domains. The Japanese variant of Dent's disease has been observed to be less severe. and we have investigated two unrelated Japanese families for CLCN5 mutations.Methods. Six patients from two unrelated families were studied. Leukocyte DNA from probands was used with CLCN5-specific primers for polymerase chain reaction (PCR) amplification of the coding region and exon-intron boundaries, and the DNA sequences of the products were determined to identify abnormalities in the gene. RNA extracted from the kidney, leukocytes, or urine sediments was used to characterize further the effects of the identified mutations.Results. beta(2)-microglobulinuria was detected in five patients, hypercalciuria in two patients, nephrolithiasis in three patients (2 of whom were females), and one 51-year-old man had renal failure. Two novel CLCN5 mutations consisting, of an a to g transition at the invariant ag acceptor splice site of intron 5 and an intragenic deletion that encompassed the region between intron 3 and intron 6 were identified. The acceptor splice site mutation led to the utilization of two alternative cryptic splice sites in exon 6 that resulted in a frameshift or skipping of the exon 6. The deletional mutation. which resulted in a loss of exons ii, 5, and 6. is predicted to lead to a loss of domains 1 through 4. Both mutations predict truncated chloride channels that are likely to result in a functional loss.Conclusions. The observations of renal failure in one male and nephrolithiasis in two females represent important new findings in this Japanese variant of Dent's disease that is associated with CLCN5 mutations. In addition, our study is the first to demonstrate the use of urinary sediment cells and renal tissue for the detection of CLCN5 transcript abnormalities. These results help to expand the spectrum of CLCN5 mutations associated with Dent's disease.