摘要：
目的 对18个21羟化酶缺陷症(21-hydroxylase deficiency,21-OHD)高风险家系进行基因筛查和胎儿产前诊断,为家系提供遗传咨询.方法 首先,采用多重连接酶扩增反应技术结合巢氏PCR和一代测序技术对18个家系的先证者(7例已死亡)及其父母进行CYP21A2基因变异检测,确定先证者及父母基因型.其次,抽取胎儿绒毛或羊水,采用亲子鉴定试验排除母体DNA污染,针对先证者或先证者父母携带的突变位点对家系中的高危胎儿进行产前基因诊断.结果 18个21-OHD高危家系的成员中共检测到10种突变,包括大片段缺失、I2G、E3del8bp、I172N、V281L、E6 cluster、L307Ffs、Q318X、R356W和R484Pfs.先证者均为CYP21A2基因纯合或复合杂合突变导致的患者,其父母均为携带者;比较短串联重复序列位点未见母体DNA污染迹象;在18个家系的胎儿中,5个家系的胎儿为患者,4个家系的胎儿为携带者,9个家系的胎儿正常.结论 CYP21A2基因突变是21-OHD的致病原因,CYP21A2基因检测为21-OHD患者的诊断及高风险家系的遗传咨询和产前诊断提供了依据.%Objective Genetic screening and prenatal diagnosis was performed in eighteen families with high risk of 21-hydroxylase deficiency (21-OHD) to provide valuable information for genetic counseling in these affected families.Methods First,multiplex ligation-dependent probe amplification (MLPA) combined with nested-PCR based Sanger sequencing was used to detect CYP21A2 gene mutations in probands and their parents of eighteen families,with seven probands had been dead.Second,paternity test was applied to exclude the possibility of maternal genomic DNA contamination,and fetal prenatal diagnosis is based on the mutations found in proband or parents of the family.Results Ten mutations were identified in these eighteen families,including large fragment deletion,I2G,E3del8bp,I172N,V281L,E6 cluster,L307Ffs,Q318X,R356W and R484Pfs.All probands were caused by homozygous or compound heterozygous mutations of CYP21A2 gene and their parents were carriers.By comparing short tandem repeat sites contamination of maternal genomic DNA was not found in fetal DNA.Prenatal diagnosis showed that five fetus were 21-OHD patients,four fetus were carriers and the other nine fetus were normal.Conclusion CYP21A2 gene mutation is the etiology of 21-OHD.Genetic testing of CYP21A2 could assist physicians in 21-OHD diagnosis and provided genetic counseling and prenatal diagnosis for parents who are at risk for having a child with congenital adrenal hyperplasia.
