COL1A1/COL1A2基因突变分析与成骨不全的产前基因诊断

目的对有成骨不全(Osteogenesis Imperfecta,OI)孕史的患者,进行系统B超及COL1A1/COL1A2基因检测,希望建立OI患儿产前诊断方案,为OI患儿进行产前诊断提供技术保障。方法对于有OI孕史的孕妇,进行系统B超监测;根据胎儿股骨、长骨的超声影像学表现,初诊为成骨不全。抽取羊水,采用直接测序法对羊水DNA的COL1A1和COL1A2基因全编码外显子及启动子区域进行突变位点检测。检出的新突变,对孕妇夫妇及家系其他成员直接测序证实。产前诊断标本均需做母血污染鉴定。结果胎儿超声影像学表现为股骨短小,胫腓骨弯曲成角,颅骨变薄且发现多处骨折,考虑OI。STR法鉴定,羊水无母血污染。DNA序列分析结果显示COL1A1基因鉴定出19个SNP位点,没有鉴定出突变位点;COL1A2基因鉴定出13个SNP位点及第36外显子的第2180位置碱基发生错义突变位点(c.2180G>A,p.Gly727Asp)。孕妇在COL1A2基因的第36外显子亦存在错义突变位点(c.2180G>A,p.Gly727Asp),但其临床特征不一致。其他成员均未检测到Gly727Asp突变。结论有OI孕史的孕妇,采取B超和COL1A1/COL1A2基因诊断技术,可以快速、有效对高危胎儿做出确诊,为预防患病胎儿出生提供技术保障。

Gene mutation analysis of COL1A1/COL1A2 and prenatal genetic diagnosis of osteogenesis imperfecta

Objective：In this study,the patients with OI pregnancy history were required to have ultrasound（US） examination and COL1A1/COL1A2 gene mutation detection.It is helpful to establish a clinical protocol for OI patient and provide the technical security for prenatal diagnosis.Methods：The pregnant woman with OI pregnancy history must be monitored by US.According to ultrasonography of fetal femur and long bone,it was diagnosed as OI.Amniotic fluid was drawn from pregnant woman with ultrasound abnormality.The sample was detected for COL1A1 and COL1A2 mutations using direct sequencing.According to the result of new mutation detection,the COL1A1 and COL1A2 genetic mutation for all family members were detected and analyzed.Identification of maternal blood contamination must be done before tests.Results：The ultrasound imaging showed that the fetus′ femur was short,tibiofibula was angled bend,skull was thinning and multiple fractures were found.So we consider fetus was OI.The sample was identified without maternal blood contamination by STR.The COL1A1 of fetus was identified with 19 SNP loci,but no mutation was found.The COL1A2 was identified with 13 SNP loci,and a G and A heterozygosis mutation at the exon 36 was found.The pregnant woman was found with the same mutation,but the clinical picture was different.Other members were tested with no detectable mutation.Conclusion：The pregnant woman with OI pregnancy history would be monitored by US and detected by genetic tests.It is very import for the sake of birth defects prevention.