| Objective:To compare and analyze the results of non-invasive prenatal testing(NIPT)and invasive prenatal diagnosis for fetal chromosome testing between the advanced maternal age and the appropriate maternal age pregnant women.To explore the application value of NIPT in prenatal screening of advanced maternal age,and to provide scientific basis for rational selection of prenatal screening and prenatal diagnosis for advanced maternal age.Methods: In this study,24 908 single pregnant women who received NIPT test voluntarily and were followed up with pregnancy outcome from January 2012 to December 2016 were selected as the subjects.According to the age of delivery,they were divided into three groups: the <35 years old pregnant women was the control group,the 35-39 years old pregnant women group,and the over 40 years old pregnant women group.All positive NIPT results should be followed up with an amniocentesis or cordocentesis to confirm the diagnosis.The karyotype analysis of trisomy 21(T21),trisomy 18(T18),trisomy 13(T13)and sex chromosome aneuploidy(SCA)were verified.Karyotype analysis combined with chromosome microarray analysis(CMA)was used to verify the high risk of microdeletions and microduplications.The negative results were verified by telephone follow-up of pregnant women with low risk indicated by NIPT within 1 year after delivery.The results of NIPT,karyotype analysis and CMA test in three groups of pregnant women were statistically analyzed by SPSS18.0 was used.Results:1.Among 24908 subjects,446 cases at high risk of fetal chromosomal aneuploidy were detected by NIPT,including 164 cases with high risk of T21,53 cases with high risk of T18,34 cases with high risk of T13 and 195 cases with high risk of SCA.The karyotype analysis confirmed 232 cases of true positive,including T21 positive 133 cases,T18 positive 31 cases,T13 positive 8 cases,SCA positive 60 cases,T21 positive detection accounted for the highest 57.33%.Compared with the results of karyotype analysis,the coincidence rate of T21 screening by NIPT was 81.09%,which was higher than T18,T13 and SCA,58.49%,23.53% and 30.77%.2.The abnormal type of fetal chromosomal aneuploidy T21 was the highest in the three groups,and the positive rate was 0.39%(72/18573)in the <35 years old group,0.66%(37/5623)in the 35-39 years group and 3.37%(24/712)in the over 40 years old group.The positive detection rate was increased with age,and the positive detection rate increased significantly over the age group above 40 years old.3.The positive rates of fetal chromosomal aneuploidy detected by NIPT were 1.68%(312/18573)in the <35 years old group,1.64%(92/5623)in 35-39 years old group and 5.90%(42/712)in over 40 years old group respectively.There was no significant difference in the positive rate between the <35 years old group and the 35-39 years old group(P > 0.05).The positive rate of the over 40 years old group was significantly higher than that of the <35 years old group and the 35-39 years old group(P < 0.05).4.The sensitivity and negative predictive value of NIPT to T21,T18 and T13 in the three groups were all 100%.The specificity of T21 screening was 99.87% in the <35 years old group,99.93% in the 35-39 years old group,99.71% in the over 40 years old group,the positive predictive value was 74.23% in the <35 years old group,90.24% in the 35-39 years old group and 92.31% in the over 40 years old group;The specificity of T18 screening was 99.91% in the <35 years old group,99.95% in the 35-39 years old group and 99.58% in the over 40 years old group,the positive predictive value was 54.29% in the <35 years old group,70.00% in the 35-39 years old group and 62.50% in the over 40 years old group;The specificity of T13 screening was 99.88% in the <35 years old group,99.95% in the 35-39 years old group and 100% in the over 40 years old group,The positive predictive value was 20.69% in the <35 years old group,25.00% in the 35-39 years old group and 100% in the over 40 years old group,of which only one sample was collected in the over 40 years old group.5.There were 69 cases high risk of microdeletions and microduplications in the three groups by NIPT,including 51 cases in the <35 years old group,15 cases in the 35-39 years old group,3 cases in the over 40 years old group,22 cases were verified positive by CMA,18 cases in the <35 years old group,2 cases in the 35-39 years old group,and 2 cases in the over 40 years old group.Karyotype analysis showed that 14 cases were verified positive,including 12 cases in the <35 years old group,1 case in the 35-39 years old group and 1 case in the over 40 years old group.Conclusion:1.T21 is the main type of fetal chromosomal aneuploidy and the positive detection rate increased with age.The positive rate of pregnant women over 40 years old increased significantly,is a major disease in prenatal diagnosis of chromosomal disorders.2.NIPT has the same screening validity in pregnant women aged 35-39 and < 35 at T21,T18 and T13.NIPT is preferred for screening.Although it has a higher screening potency in pregnant women aged over 40,other risk factors should be considered.In clinical practice,It can be used careful and to be an alternative program.3.NIPT screening for microdeletion and microduplication currently only has a certain role in suggesting that the diagnosis needs to be combined with karyotype analysis and CMA. |
PDF Full Text Request