The Application Value Of Noninvasive DNA Detection In Fetal Sex Chromosome Abnormality Detection

Objective To explore the application value of non-invasive Prenatal Testing(NIPT)in the detection of sexual chromosome abnormalities,and to accumulate valuable clinical data for NIPT in the Prenatal screening of sexual chromosome diseases.Methods A total of 33 pregnant women with a single live fetus who were diagnosed with high risk of sex chromosomes and underwent amniocentesis with informed consent by NIPT in the maternal and child health hospital of Inner Mongolia autonomous region from January 2018 to December 2019 were selected as the study population.Genetic testing of fetal,placental and maternal peripheral blood was carried out in these cases,and pregnancy outcome was tracked.The results were compared to evaluate the application value of NIPT in the screening of sexual chromosome abnormalities.Results NIPT detection results show that the sex chromosomes of 33 cases of pregnant women at high risk of amniotic fluid karyotype analysis,except 1 case of amniotic fluid training failure outside the rest of the 32 cases,13 cases of false positives,19 cases with NIPT results conform to,positive results of 47 respectively,XXY4 example,47,XYY4 example,47,XXX8 example,45,the X1 example,there are 2 cases as chimeras,karyotype were 45,X / 46(9),XX(41)and 48,XXX,+ 20(15)/ 47,XXY(35).In this study,1 case of NIPT screening was 45,X/dup(8p23.3-p23.1,8.35m-m).In this sample,-M represented from the mother source,the amniotic fluid cell culture failed,and the CMA result was normal karyotype(46,XN).Statistics showed that the total positive predictive value of NIPT for sex chromosome abnormality was 57.58%(19/33).For 45,X positive predictive value was 20.00%(2/10),47,XXX positive predictive value was 72.73%(8/11),47,XXY positive predictive value was 83.33%(5/6),47,XYY positive predictive value was 80.00%(4/5).NIPT detection of false positive sex chromosomes was associated with placental karyotype abnormality and maternal karyotype abnormalit y.Conclusion 1.NIPT has the advantages of simple operation,no culture,high cost performance and no trauma,etc.It can screen out sex chromosome number abnormality,sex chromosome chimera and copy number variation(CNV)in sex chromosome abnormality,which has certain clinical application value.2.The positive predictive value of sex chromosome monomer screened by NIPT was lower than that of trisomy.The chromosome of pregnant woman and placenta should be considered synthetically during diagnosis.3.The high risk of sex chromosome in NIPT screening still needs to be further confirmed by traditional karyotype analysis.On the basis of karyotype analysis,FISH,CMA and other technologies can be combined as effective supplementary means.