一个遗传性多发性骨软骨瘤家系的基因变异分析

Analysis of genetic variants in a pedigree affected with hereditary multiple osteochondroma

目的对1个遗传性多发性骨软骨瘤家系进行基因变异检测,明确其可能的致病原因。方法提取先证者及其家系成员的外周血基因组DNA,用二代测序技术(next generation sequencing,NGS)筛查先证者EXT1/EXT2编码区及邻近内含子序列,对疑似致病变异进行先证者及家系成员Sanger测序和酶切验证。结果NGS检测结果显示先证者EXT1基因第10外显子存在c.1911C>A杂合无义变异,Sanger测序验证家系中先证者及父亲均检测到该变异,而先证者三姐及对照均未携带该变异。根据美国医学遗传学与基因组学学会遗传变异分类标准与指南,判定EXT1基因c.1911C>A变异为致病性变异(PVS1+PM2+PP1)。结论EXT1基因的c.1911C>A可能是该家系的致病原因,该变异的检出拓展了遗传性多发性骨软骨瘤的基因变异谱。

Objective To explore the genetic basis for a pedigree affected with hereditary multiple osteochondroma(HMO).Methods Peripheral blood samples were collected from the proband and members of his pedigree with informed consent.Following extraction of genomic DNA,all coding exons and flanking intronic sequences(-10 bp)of the EXT1 and EXT2 genes were subjected to targeted capture and next generation sequencing(NGS).Suspected variant was verified by Sanger sequencing.Results A heterozygous nonsense variant(c.1911C>A)was found in exon 10 of the EXT1 gene in the proband and his affected father but not in a healthy sister and normal controls.The variant was classified as a pathogenic based on the guidelines of the American College of Medical Genetics and Genomics(PVS1+PM2+PP1).Bioinformatic analysis predicted that the c.1911C>A variant may be disease-causing via nonsense-mediated mRNA decay and anomalous splicing.Conclusion The c.1911C>A variant probably underlay the disease in this pedigree.Discovery of this variant enriched the variant spectrum of HMO.