外显子组测序在抗肌萎缩蛋白基因检测到一个新的剪接供体位点突变

Exome sequencing discovered a novel splice donor mutation in dystrophin gene

目的应用外显子组捕获和第2代测序技术检测抗肌萎缩蛋白基因(dystrophin)中的微小突变。方法通过外显子组捕获和第2代测序技术对1例具有典型杜氏肌营养不良症(DMD)临床表现但没有外显子缺失或重复的患者进行dtstriogub基因突变检测,并用Sanger测序证实检测结果。以生物信息学预测基因突变所致该基因编码情况的改变。以患者母亲和100名体检正常者作为对照。结果在患者dystrophin基因内含子50的第1个碱基检测到1个碱基改变:G>C,其母亲在相同的位置发生了杂合改变。生物信息学预测此改变将使内含子50原有的5'剪接位点消失,导致其相应肽链C端氨基酸序列改变、终止密码提前出现。Sanger测序进一步证实了该突变的存在,且在正常对照未检测到该突变。这是在dystrophin基因上新发现的致病性剪接供体位点突变。结论外显子组测序技术可有效检测dystrophin基因微小突变,其应用可进一步完善DMD分子诊断体系。

Objective To detect subtle mutations in the dystrophin gene by exome capturing using second-generation sequencing technique. Methods Exome capturing using second-generation sequencing technique was used to detect mutations of dystrophin gene in a patient with typical clinical manifestations of Duchenne muscular dystrophy （DMD）, but without deletions or duplications in the dystrophin gene. The mutations were verified by Sanger sequencing, and bioinformatics was employed to predict its influence on the coding. The patient＇s mother and 100 healthy volunteers were taken as controls. Results A base change in the first base of intron 50 （G〉C） was found in dystrophin gene of the patient, and his mother was heterozygosis at the same site. Bioinformatics predicted that the 5＇ donor splicing site of intron 50 would disappear due to this base change, which would alter the amino acid sequence at the C terminal of corresponding peptide and result in the appearance of premature termination codon. Sanger sequencing confirmed that the base change was a novel pathogenic mutation in the dystroDhin gene, and it was absent in normal controls. Conclusion It is demonstrated that exome sequencing technique can effectively detect the subtle mutations in the dystrophin gene, which may contribute to better molecular diagnosis of DMD.