成骨发育不全家系遗传学分析及植入前遗传学诊断研究

Familial genetic analysis of osteogenesis imperfecta and the study on preimplantation genetic diagnosis

目的探讨植入前遗传学诊断在成骨发育不全出生缺陷预防中的应用价值。方法针对2015年5月在安徽医科大学第一附属医院妇产科生殖医学中心就诊的1例成骨发育不全家系行外显子捕获测序筛查突变位点,并通过一代测序验证COL1A2基因突变。选择COL1A2基因上下游1 Mb区域42个单核苷酸多态性高频突变位点及基因编码区作为目标区域,构建患者夫妇的单体型。结合连锁分析及直接测序,完成植入前遗传学诊断。结果患者存在COL1A2基因c.982G>T(p.Gly328Cys)的致病性突变,受累引产胎儿遗传了母亲的致病性突变。经植入前遗传学诊断,患者夫妇的9个囊胚中6个正常,3个受累。选择发育良好且遗传学正常的胚胎植入母体子宫后,足月分娩一健康婴儿。结论该研究是中国COL1A2基因突变植入前遗传学诊断的首例报道。结合选择性遗传标记连锁分析和突变位点直接测序进行植入前遗传学诊断,是单基因遗传病出生缺陷的有效预防手段。

Objective To explore the application of preimplantation genetic diagnosis in the prevention of osteogenesis imperfecta. Methods For one case of osteogenesis imperfecta seeking consultation in the Reproductive Medicine Center of the First Affiliated Hospital of Anhui Medical University in May 2015, exon sequencing and Sanger sequencing were performed to screen and verify pathogenic mutation site on COL1A2 gene. A set of 42 high-frequency SNPs within 1 Mb region around the COL1A2 gene were selected to construct the haplotype of the patient couple. Preimplantation genetic diagnosis （PGD）was accomplished by haplotype linkage analysis and direct sequencing.Results The female patient and her affected fetus both carried c.982G〉T （p.Gly328Cys）pathogenic mutation in the COL1A2 gene. PGD was subsequently performed. The results showed that 6 embryos were normal and 3 were affected. One well-developed and genetically normal embryo was transferred. A healthy baby was delivered at term.Conclusion This study is the first report of preimplantation genetic diagnosis of COL1A2 gene mutations in China. Combining selective genetic marker linkage analysis with direct sequencing of mutation sites for PGD is an effective way to prevent birth defects of single-gene inherited diseases.