摘要目的:对孕早、中期孕妇进行脆性X智力低下1(fragile X mental retardation 1，FMR1)基因筛查，为携带高风险CGG重复数者提供产前诊断。方法:采集2316名12～21 +6周的孕妇的外周血样，提取基因组DNA，用荧光PCR-毛细管电泳法检测FMR1的CGG重复次数。对3例携带前突变者提供遗传咨询及产前诊断。 结果:FMR1基因CGG重复数中间型携带率为1/178，前突变携带率为1/772，未发现全突变患者或携带者。CGG重复最大频率等位基因为29次，占比49.29%，其次为30次(28.56%)、36次(8.83%)。病例1孕12 +5周绒毛染色体检查示胎儿核型为45，X，FMR1基因CGG重复数为前突变，经遗传咨询后引产。其父母的重复数分别为70/-次、29/30次。病例2于孕20周行羊膜腔穿刺，胎儿FMR1基因CGG重复数为29/-次，染色体核型及染色体拷贝数变异检测均未见异常，选择继续妊娠。病例3经遗传咨询后拒绝产前诊断，足月顺产一女婴，出生体重2440 g，随访未见明显异常。 结论:孕妇应在早、中期进行FMR1基因筛查，携带高风险CGG重复数者应进行产前诊断、遗传咨询和家系筛查。

abstractsObjective:To screen for mutations of fragile X mental retardation 1 (FMR1) gene during early and middle pregnancy and to provide prenatal diagnosis for those carrying high-risk CGG trinucleotide expansions.Methods:Peripheral blood samples of 2316 pregnant women at 12 to 21 + 6 gestational weeks were collected for the extraction of genomic DNA. CGG repeats of the FMR1 gene were detected by fluorescence PCR and capillary electrophoresis. Genetic counseling and prenatal diagnosis were provided for 3 women carrying the premutations. Results:The carrier rate of CGG repeats of the FMR1 gene was 1 in 178 for the intermediate type and 1 in 772 for the premutation types. The highest frequency allele of CGG was 29 repeats, which accounted for 49.29%, followed by 30 repeats (28.56%) and 36 repeats (8.83%). In case 1, the fetus had a karyotype of 45, X, in addition with premutation type of CGG expansion of the FMR1 gene. Following genetic counseling, the couple chose to terminate the pregnancy through induced labor. The numbers of CGG repeats were respectively 70/- and 29/30 for the husband and wife. In case 2, amniocentesis was performed at 20 weeks of gestation. The number of CGG repeats of the FMR1 gene was 29/-. No abnormality was found in the fetal karyotype and chromosomal copy number variations. The couple chose to continue with the pregnancy. Case 3 refused prenatal diagnosis after genetic counseling and gave birth to a girl at full term, who had a birth weight of 2440 g and no obvious abnormality found during follow-up.Conclusion:Pregnant women should be screened for FMR1 gene mutations during early and middle pregnancy, and those with high-risk CGG expansions should undergo prenatal diagnosis, genetic counseling and family study.