三核苷酸重复引物PCR和甲基化特异性多重连接探针扩增技术在脆性X综合征产前诊断中的应用

目的探讨脆性X综合征(FXS)产前基因诊断的方法。方法采用三核苷酸重复引物PCR法(TP-PCR)及甲基化特异性多重连接探针扩增技术(MS-MLPA)检测2个FXS家系及30例正常对照胎儿样本FMR1基因CGG重复数、AGG排布及FMR 1基因Cp G岛甲基化状态。结果正常对照FMR1基因(CGG)n重复数介于23~40之间,频数最大的重复数为29,AGG排布式以9A9A9最为常见。2个FXS家系中前突变等位基因向子代遗传过程中均发生了CGG扩展。正常对照及前突变携带者FMR1基因Cp G岛均为低甲基化状态,全突变患者Cp G岛为高甲基化状态。结论 TP-PCR和MS-PCR联合应用能够检出胎儿FMR1基因CGG重复数和Cp G岛甲基化状态,从而判断胎儿是否为脆性X综合征患儿,为优生干预提供可靠的依据。

Application of triplet repeat-primed-PCR and methylation specific multiplex ligation-dependent probe amplification in prenatal diagnosis of fragile X syndrome

Objective To explore the application value of triplet repeat-primed (TP)-PCR and methylation specific multiplex ligation-dependent probe amplification (MS-MLPA) for prenatal diagnosis of Fragile X syndrome.Methods The CGG repeat number and AGG interruption pattern were analyzed using TP-PCR and methylation status of CpG islands was detected by MS-MLPA from 2 FXS family members and 30 unrelated fetuses.Results The range of alleles was 23-40 CGG repeats in fetuses,and the most frequent allele and AGG interruption pattern were 29 CGG repeats and 9A9A9,respectively.CGG expansion was observed in both of the two permutation alleles during transmission.CpG islands ofFMR 1 were observed hypermethylated in patients with full mutation,while 30 controls and premature carders were hypomethylation.Conclusion TP-PCR,in combination with MS-MLPA,represents a reliable diagnostic protocol in the prenatal diagnosis of FXS.