Two novel mutations of CLCN7 gene in Chinese families with autosomal dominant osteopetrosis (type II)
Two novel mutations of CLCN7 gene in Chinese families with autosomal dominant osteopetrosis (type II)
复制标题
中国常染色体显性骨石症（II型）家系中CLCN7基因的两个新突变。
DOI：
10.1007/s00774-015-0682-2
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发表时间：
2016-07-01
影响因子：
3.3
通讯作者：
Zhang, Zhen-Lin
中科院分区：
文献类型：
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作者：
Zheng, Hui;Shao, Chong;Zhang, Zhen-Lin
常染色体显性遗传性骨质疏松症II型(ADO-II)是一种以骨硬化为特征的遗传性骨病，主要累及脊柱(椎体终板增厚，或橄榄球状脊柱)、骨盆(骨中骨结构)和颅底。氯离子通道7(CLCN7)已被报道为致病基因。在这项研究中，我们的目的是确定四个中国ADO-II家系的致病突变。对来自中国人ADO-II家系的4个先证者的CLCN7基因的全部25个外显子(包括外显子-内含子边界)进行了直接扩增和测序。然后在其他家庭成员和250名健康对照中确定了突变位置。在家系1中，在先证者中发现了CLCN7基因外显子4中已知的错义突变c.296A和gt；G，导致第99(Y99C)位酪氨酸(UAU)替换为半胱氨酸(UGU)；该突变也在其患病的父亲中发现。在家系2中，在先证者中发现了一个新的外显子10的错义突变c.865G>；C，导致第289位(V289L)的Valine(GUC)替换为亮氨酸(CUC)，该突变也在她的健康母亲和姐姐中发现。在家系3中，在先证者中发现了CLCN7基因第17外显子上的一个新的错义突变c.1625C>；T，导致了位于p.542(A542V)的丙氨酸(GCG)到缬氨酸(Gug)的替换；在她的父亲中也发现了该突变。在家系4中，在先证者的第24外显子中发现了一个热点R767W(c.2299C>；T，CGG>；TGG)，这再次证明了该位点的易感性或在不同种族中具有相似的遗传背景。此外，通过对8种脊椎动物的蛋白质序列进行比较，发现V289L和A542V这两个新的突变发生在一个高度保守的位置，PolyPhen-2软件预测它们具有致病作用，得分约为1。在250名健康对照中未发现这些突变位点。我们的研究结果提示，CLCN7基因中新的错义突变V289L和A542V是导致这两个中国人家系发生ADO-II的原因。
Autosomal dominant osteopetrosis type II (ADO-II) is a heritable bone disorder characterized by osteosclerosis, predominantly involving the spine (vertebral end-plate thickening, or rugger-jersey spine), the pelvis ("bone-within-bone" structures) and the skull base. Chloride channel 7 (CLCN7) has been reported to be the causative gene. In this study, we aimed to identify the pathogenic mutation in four Chinese families with ADO-II. All 25 exons of the CLCN7 gene, including the exon-intron boundaries, were amplified and sequenced directly in four probands from the Chinese families with ADO-II. The mutation site was then identified in other family members and 250 healthy controls. In family 1, a known missense mutation c.296A > G in exon 4 of CLCN7 was identified in the proband, resulting in a tyrosine (UAU) to cysteine (UGU) substitution at p.99 (Y99C); the mutation was also identified in his affected father. In family 2, a novel missense mutation c.865G > C in exon 10 was identified in the proband, resulting in a valine (GUC) to leucine (CUC) substitution at p.289 (V289L); the mutation was also identified in her healthy mother and sister. In family 3, a novel missense mutation c.1625C > T in exon 17 of CLCN7 was identified in the proband, resulting in an alanine (GCG) to valine (GUG) substitution at p.542 (A542V); the mutation was also identified in her father. In family 4, a hot spot, R767W (c.2299C > T, CGG > TGG), in exon 24 was found in the proband which once again proved the susceptibility of the site or the similar genetic background in different races. Moreover, two novel mutations, V289L and A542V, occurred at a highly conserved position, found by a comparison of the protein sequences from eight vertebrates, and were predicted to have a pathogenic effect by PolyPhen-2 software, which showed "probably damaging" with a score of approximately 1. These mutation sites were not identified in 250 healthy controls. Our present findings suggest that the novel missense mutations V289L and A542V in the CLCN7 gene were responsible for ADO-II in the two Chinese families.