Genetic analysis ofCOL1A1 andCOL1A2 genes in two fetuses with osteogenesis imperfecta phenotype
扫码查看
点击上方二维码区域，可以放大扫码查看
原文链接
万方数据
目的 探讨2例成骨不全症(OI)胎儿的临床表型及遗传学特征，明确致病原因。 方法 收集分别在2021年6月11日和2021年10月16日就诊于潍坊医学院附属医院的2例中孕期超声诊断疑似OI胎儿的临床资料信息。采集孕妇羊水及胎儿父母、亲属外周血样品提取基因组DNA，对2例胎儿进行全外显子组测序(WES)，对候选变异进行Sanger家系验证。针对可能影响pre-mRNA剪接的变异，利用minigene体外分析变异位点附近外显子的剪接方式，对变异的致病性进行判定。 结果 胎儿1在胎龄17+6周超声显示双侧肱骨和股骨发育落后2周余，四肢长骨多发骨折、成角畸形。胎儿2在胎龄23周超声显示双侧肱骨和股骨发育分别落后1+周和4周，双侧股骨和胫腓骨弯曲。WES结果显示胎儿1的COL1A1基因第49外显子存在c.3949_3950insGGCATGT(p.N1317Rfs*114)杂合变异，该变异导致翻译提前终止，胎儿父母外周血中未检出该变异。根据美国医学遗传学与基因组学学会(ACMG)变异评级指南，c.3949_3950insGGCATGT变异评级为致病性变异(PVS1+PS2+PM2_Supporting)。胎儿2的COL1A2基因第26内含子中存在父源的c.1557+3A>G杂合变异，剪接报告基因分析提示该变异使COL1A2基因pre-mRNA第26外显子发生跳跃，导致mRNA转录本第1 504~1 557位编码序列整码缺失及其编码蛋白第502~519位氨基酸缺失，根据ACMG变异评级指南，c.1557+3A>G杂合变异评级为致病性变异(PS3+PM1+PM2_Supporting+PP3+PP5)。 结论 COL1A1基因c.3949_3950insGGCATGT变异、COL1A2基因c.1557+3A>G变异分别可能为2例OI胎儿的遗传学原因。COL1A1基因c.3949_3950insGGCATGT的发现丰富了成骨不全致病基因变异谱。 Objective To explore the genetic basis of two fetuses with an osteogenesis imperfecta (OI) phenotype. Methods Two fetuses diagnosed at the Affiliated Hospital of Weifang Medical College respectively on June 11, 2021 and October 16, 2021 were selected as the study subjects. Clinical data of the fetuses were collected. Amniotic fluid samples of the fetuses and peripheral blood samples of their pedigree members were collected for the extraction of genomic DNA. Whole exome sequencing (WES) and Sanger sequencing were carried out to identify the candidate variants. Minigene splicing reporter analysis was used to validate the variant which may affect the pre-mRNA splicing. Results For fetus 1, ultrasonography at 17+ 6 weeks of gestation had revealed shortening of bilateral humerus and femurs by more than two weeks, in addition with multiple fractures and angular deformities of long bones. WES revealed that fetus 1 had harbored a heterozygous c. 3949_3950insGGCATGT (p.N1317Rfs*114) variant in exon 49 of the COL1A1 gene (NM_000088.4). Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), it was classified as a pathogenic variant (PVS1+ PS2+ PM2_Supporting) for disrupting the downstream open reading frame resulting in premature translational termination, being de novo in origin, and lacking records in the population and disease databases. For fetus 2, ultrasonography at 23 weeks of gestation also revealed shortening of bilateral humerus and femurs by one and four weeks, respectively, in addition with bending of bilateral femurs, tibias and fibulas. Fetus 2 had harbored a heterozygous c. 1557+ 3A>G variant in intron 26 of theCOL1A2 gene (NM_000089.4). Minigene experiment showed that it has induced skipping of exon 26 from the COL1A2 mRNA transcript, resulting in an in-frame deletion (c.1504_1557del) of the COL1A2 mRNA transcript. The variant was inherited from its father and had been previously reported in a family with OI type 4. It was therefore classified as a pathogenic variant (PS3+ PM1+ PM2_Supporting + PP3+ PP5). Conclusion The c. 3949_3950insGGCATGT (p.N1317Rfs*114) variant in the COL1A1 gene and c. 1557+ 3A>G variant in theCOL1A2 gene probably underlay the disease in the two fetuses. Above findings not only have enriched the mutational spectrum of OI, but also shed light on the correlation between its genotype and phenotype and provided a basis for genetic counseling and prenatal diagnosis for the affected pedigrees.
Objective To explore the genetic basis of two fetuses with an osteogenesis imperfecta (OI) phenotype. Methods Two fetuses diagnosed at the Affiliated Hospital of Weifang Medical College respectively on June 11, 2021 and October 16, 2021 were selected as the study subjects. Clinical data of the fetuses were collected. Amniotic fluid samples of the fetuses and peripheral blood samples of their pedigree members were collected for the extraction of genomic DNA. Whole exome sequencing (WES) and Sanger sequencing were carried out to identify the candidate variants. Minigene splicing reporter analysis was used to validate the variant which may affect the pre-mRNA splicing. Results For fetus 1, ultrasonography at 17+ 6 weeks of gestation had revealed shortening of bilateral humerus and femurs by more than two weeks, in addition with multiple fractures and angular deformities of long bones. WES revealed that fetus 1 had harbored a heterozygous c. 3949_3950insGGCATGT (p.N1317Rfs*114) variant in exon 49 of the COL1A1 gene (NM_000088.4). Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), it was classified as a pathogenic variant (PVS1+ PS2+ PM2_Supporting) for disrupting the downstream open reading frame resulting in premature translational termination, being de novo in origin, and lacking records in the population and disease databases. For fetus 2, ultrasonography at 23 weeks of gestation also revealed shortening of bilateral humerus and femurs by one and four weeks, respectively, in addition with bending of bilateral femurs, tibias and fibulas. Fetus 2 had harbored a heterozygous c. 1557+ 3A>G variant in intron 26 of theCOL1A2 gene (NM_000089.4). Minigene experiment showed that it has induced skipping of exon 26 from the COL1A2 mRNA transcript, resulting in an in-frame deletion (c.1504_1557del) of the COL1A2 mRNA transcript. The variant was inherited from its father and had been previously reported in a family with OI type 4. It was therefore classified as a pathogenic variant (PS3+ PM1+ PM2_Supporting + PP3+ PP5). Conclusion The c. 3949_3950insGGCATGT (p.N1317Rfs*114) variant in the COL1A1 gene and c. 1557+ 3A>G variant in theCOL1A2 gene probably underlay the disease in the two fetuses. Above findings not only have enriched the mutational spectrum of OI, but also shed light on the correlation between its genotype and phenotype and provided a basis for genetic counseling and prenatal diagnosis for the affected pedigrees.
万方数据
