1例携带者筛查意外发现的X染色体长臂部分缺失孕妇的遗传学分析及产前诊断

Genetic analysis and prenatal diagnosis of a pregnant woman with a partial deletion of X chromosome by expanded carrier screening

目的对携带者筛查意外发现的1例X染色体长臂部分缺失的孕妇进行遗传学分析并为其提供产前诊断。方法提取孕妇外周全血基因组DNA进行基于毛细管电泳技术的携带者筛查,采用多重连接依赖探针扩增技术(MLPA)和染色体微阵列芯片分析(CMA)进行验证,染色体核型G显带技术分析外周血染色体核型,并提取羊水胎儿脱落细胞DNA进行CMA分析。结果携带者筛查的结果提示孕妇携带PLP1基因杂合缺失,MLPA结果提示孕妇PLP1基因第2~8号外显子杂合缺失,染色体核型和CMA结果均证实其携带X染色体q13.3q23区段杂合缺失,且胎儿羊水细胞存在同样片段的染色体杂合缺失,最终决定终止妊娠。结论扩展性携带者筛查发现孕妇X染色体长臂部分缺失,并将其传递给胎儿。

Objective To conduct the genetic analysis and prenatal diagnosis for a pregnant woman with Xq deletion identified by expanded carrier screening.Methods The genomic DNA of a pregnant woman was extracted for carrier screening based on capillary electrophoresis.Multipl ex ligation-dependent probe amplification(MLPA)and chromosomal microarray analysis(CMA)were applied to validate the identified variation,G-banding technique was used to analyze the karyotypes of the subject and the DNA of fetal exfoliated cells in amniotic fluid were analyzed by CMA.Results Expanded carrier screening hinted that the pregnant woman was a heterozygous carrier for the deletion of the PLP1 gene.MLPA analysis has revealed removal of exons 2 to 8 of the PLP1 gene.A heterozygous deletion in Xq13.3q23 was identified by CMA and G-banding technique.Fetal amniotic fluid cells had the same fragment of heterozygous deletion and decided to terminate the pregnancy.Conclusion A pregnant female was identified as a carrier for Xq deletion by expanded carrier screening and the fetus inherited this deletion.