一例SRY阳性46,XX男性综合征胎儿的产前诊断

Prenatal diagnosis of a fetus with 46,XX(SRY positive)male syndrome

目的对一例无创产前筛查提示性染色体异常(XXY)胎儿进行遗传学检测,明确其产前诊断结果,以提供合理的遗传咨询。方法对胎儿羊水细胞进行G显带核型分析、荧光原位杂交(fluorescence in situ hybridization,FISH)检测和染色体微阵列分析(chromosome microarray analysis,CMA),同时结合胎儿外生殖器多普勒超声结果进行判断。用胎儿父母及哥哥的外周血样进行家系验证。结果G显带核型分析显示胎儿羊水染色体核型为46,XX;CMA检测发现胎儿存在2.635 Mb的Yp11.2和3.706 Mb的Yp11.31p11.2染色体区域;SRY位点FISH检测结果提示Y染色体短臂上的SRY基因片段易位到了X染色体短臂末端。胎儿父母和哥哥的外周血染色体核型和CMA结果均未见异常。诊断胎儿为SRY阳性46,XX男性综合征患者,其性染色体上的异常区段为新发突变。结论G显带核型分析、FISH检测和CMA等技术的联合使用,相互验证对于得出精准的产前诊断结果,准确指导妊娠具有重要的意义。

Objective To carry out genetic testing for a XXY fetus suggested by non-invasive prenatal testing(NIPT).Methods G-banding karyotyping,fluorescence in situ hybridization(FISH)and chromosomal microarray analysis(CMA)were performed on amniocytes from the fetus.The genitalia of the fetus was also examined by Doppler ultrasonography.The result was verified with peripheral blood samples from its parents and a brother.Results The fetus was found to have a 46,XX karyotype.CMA showed presence of sequences from Yp11.2(2.635 Mb)and Yp11.31p11.2(3.706 Mb).FISH assay suggested that the SRY fragment on Yp has translocated to Xpter.No karyotypic or pathogenic CNVs was detected in its parents and brother.The fetus was ultimately diagnosed with 46,XX(SRY positive)male syndrome.Conclusion The combination of G-banding karyotyping,FISH,and CMA is of great significance for attaining accurate prenatal diagnosis for this fetus.