[Prenatal gene diagnosis of 200 fetuses at high risk of osteogenesis imperfect].

Objective: The authors aim to provide genetic counselling and prenatal gene diagnosis to the families with osteogenesis imperfecta(OI), based on the identification of pathogenetic mutations in large cohort genetic testing. Methods: DNA was extracted from the peripheral blood of parents of the fetuses, and from the villi tissue, amniotic fluid or cord blood of the fetuses using a standard sodium dodecyl sulfate-proteinase K-phenol/chloroform extraction method. PCR combined with Sanger DNA sequencing was performed to validate the pathogenic mutations of 200 fetuses at risk of OI and their parents from 158 families. Allelic analysis of microsatellite markers was applied to exclude the false positive caused by maternal DNA contamination, when both the fetus and the mother harbored the same pathogenic genotype. Results: A total of 83 affected fetuses (83/200, 41.5%) and 12 (12/200, 6.0%) recessive carriers were identified among the 200 fetuses. The 83 affected fetuses included 78 heterozygotes (45 of COL1A1, 32 of COL1A2, one of IFITM5), and 5 compound heterozygotes or homozygotes of recessive OI (two of FKBP10, one of SEC24D, one of WNT1 and one of CRTAP); The 12 recessive carriers included 7 of WNT1, 4 of SERPINF1 and one of SERPINH1. Maternal DNA contamination was excluded from the genomic DNA samples of OI fetuses when their mother with the same affected genotypes. Conclusion: In this study, the authors used an optimized gene diagnosis system of OI to perform prenatal genetic diagnosis to 200 fetuses at high risk of OI, and provided precisely genetic counselling to the OI families.目的： 在完成大样本成骨不全症（OI）家系致病基因突变鉴定的基础上，为OI高风险胎儿提供遗传咨询和产前诊断。 方法： 采用酚/氯仿法提取先证者与胎儿父母外周血及胎儿绒毛、羊水细胞或脐带血基因组DNA；联合应用聚合酶链反应（PCR）-Sanger测序方法对来自158个OI家系的200例高风险胎儿和他们的父母进行相应位点的基因型鉴定；当胎儿与其母均为患病基因型时，应用微卫星标记等位基因分析的方法排除因胎儿基因组样本的母源DNA污染造成的假阳性。 结果： 在200例OI高风险胎儿中检出OI患者83例（41.5%），隐性遗传携带者12例（6.0%）。83例OI胎儿中包含COL1A1突变杂合子45例，COL1A2突变杂合子32例，IFITM5突变杂合子1例，FKBP10复合杂合突变2例，WNT1纯合突变1例，SEC24D复合杂合突变1例和CRTAP突变复合杂合子1例；12例隐性遗传携带者中包含WNT1杂合子7例、SERPINF1杂合子4例和SERPINH1杂合子1例；当母亲和胎儿同为OI致病基因型时，胎儿基因组DNA样本未见母源DNA污染，排除了胎儿假阳性可能。 结论： 本研究建立了较完善的OI产前基因诊断体系，为200例OI高风险胎儿提供了产前基因诊断和精准遗传咨询。.