两个遗传性多发性软骨瘤家系EXT1及EXT2基因的突变检测

Analysis of EXT1 and EXT2 gene mutations in two Chinese pedigrees affected with hereditary multiple exostosis

目的 对两个遗传性多发性软骨瘤(hereditary multiple exostosis,HME)家系致病基因EXT1和EXT2的编码区进行突变分析.方法 应用二代测序(next-generation sequencing,NGS)对两名先证者进行检测,对疑似突变采用Sanger双向测序对其家系成员和200例健康对照进行验证,并应用qPCR定量或多重连接探针扩增(multiple ligation-dependent probe amplification,MLPA)技术在其家系成员中进行缺失或重复验证.结果 在两个家系中分别发现了EXT1和EXT2基因的突变.家系1先证者及父亲均携带EXT2基因c.337 338insG突变,既往未见报道.在该家系的健康成员和200例健康对照中均未检测到上述突变.家系2先证者及母亲均携带EXT1基因的缺失,其父亲未携带相同的缺失.结论 EXT1、EXT2基因的突变是两个家系的致病原因.NGS结合Sanger测序、qPCR定量分析以及MLPA可以快速准确地对HME进行基因诊断.

Objective To detect EXT1 and EXT2 gene mutations in two pedigrees affected with hereditary multiple exostosis(HME).Methods The coding regions and exon/intron boundaries of the EXT1 and EXT2 genes were analyzed by targeted next-generation sequencing(NGS).Suspected mutations were confirmed by Sanger sequencing of probands,family members and 200 unrelated healthy controls.Gross deletion was confirmed by quantitative PCR(qPCR)analysis and multiple ligation-dependent probe amplification(MLPA)analysis.Results Two mutations were detected in the pedigrees,which included EXT2 gene c.337_338insG mutation in pedigree 1 and deletion of entire EXT1 in pedigree 2.Analysis of sequencing data revealed that a novel heterozygous mutation(c.337_338insG)in EXT2 gene in proband 1 and his father.The same mutation was not found among healthy family members and 200 unrelated healthy controls.By NGS and MLPA analysis,proband 2 carried a heterozygous deletion of entire EXT1 gene.The same deletion was also found in her mother by qPCR.Conclusion Mutations of the EXT1 and EXT2 genes probably underlie the HME in both pedigrees.NGS combined with Sanger sequencing,qPCR and MLPA is effective for attaining the diagnosis.