NF1基因新突变及我国首例NF1基因拷贝数目变异报道  

One novel mutation and copy number variation of NF1gene in Chinese patients with type 1 neurofibromatosis

作　　者：邓佳[1] 邓伟平[2] 钟诚[1] 胡彬[1] 王一鸣[1] 

机构地区：[1]中山大学中山医学院医学遗传学教研室 [2]广东省人民医院皮肤科,广东广州510080

出　　处：《中国病理生理杂志》2013年第2期320-323,共4页Chinese Journal of Pathophysiology

基　　金：教育部新教师专项基金资助项目(No.20100171120055);广州市科技计划(No.2010J-E191);广东省科技计划(No.2012B032000013)

摘　　要：目的:对2例散发性1型神经纤维瘤患者进行致病基因NF1编码序列的突变筛查以及拷贝数变异(copy number variation,CNV)研究,寻找致病性突变。方法:PCR扩增NF1基因的编码区及外显子-内含子交界区,对产物进行直接测序。在50例正常对照中进行新发现突变位点的测序分析,以排除多态性。用多重连接探针扩增技术(MLPA)对患者进行NF1基因CNV的检测,并对证实有NF1拷贝缺失的患者进行长片段PCR,以找寻断裂点。结果:患者S736于NF1基因检测到一个国际上尚未报道的新突变:c.6345_6346 ins G(p.Leu2116Alafs*4),患者父母均不携带此突变,故此突变为一个de novo突变。该突变使开放阅读框移位,提前引入终止密码子,导致蛋白质分子的截断,以致部分犰狳式褶皱(ARM-type fold)结构域丢失。在另一患者S743中检测到一个包含整个NF1基因的大片段缺失,缺失区域为1.3～1.9 Mb,但断裂点尚不明,此为我国首例NF1基因拷贝数目变异的报道。结论:患者NF1基因的de novo突变及CNV是引起这2例1型神经纤维瘤发病的分子机制,这些发现可用于临床1型神经纤维瘤的分子诊断。AIM： To investigate the mutations and the copy number variation of neurofibromatosis 1 （NF1） gene in 2 sporadic patients with type 1 neurofibromatosis in China. METHODS： All coding exons and exon-intron bounda- ries of NF1 were amplified by PCR. The PCR products were sequenced. The DNA samples from 50 normal subjects were also sequenced for control. Multiplex ligation-dependent probe amplification （MLPA） was also employed to detect the copy number variation of NF1 gene in these patients. Long range PCR was used for the identification of the breakpoint in the large deletion of the gene. RESULTS： The novel mutation, c. 6345_6346 ins G （p. Leu2116Alafs ＊ 4）, was detected in patient $736. This mutation was absent in her parents and the controls, indicating a de novo mutation. It caused open reading frame shifting, introducing a premature stop codon and resulting in the truncation of the 721 amino acids at the C terminus of the wild-type protein. This truncation cut off part of the armadillo （ARM）-type fold domain in the wild-type protein. A 1.3 1.9 Mb deletion of the gene was also detected in the other patient $743. The deletion spanned the whole NF1 gene and part of the flanking regions in both ends, but the breaking point was still unknown. CONCLUSION： We have identified a novel mutation of NF1, c. 6345_6346 ins G （p. Leu2116Alafs ＊ 4）. We also first report the copy number variation of NF1 gene in Chinese patients. The investigation will be helpful for the molecular diagnosis and understanding the pathogenesis of the dis-ease.

关 键 词：基因 神经纤维瘤病1 DE novo突变 拷贝数目变异 

分 类 号：R363[医药卫生—病理学]