Objective To explore the clinical significance of non-invasive prenatal testing(NIPT)for fetal chromosomal abnormalities in the cases of twin pregnancy and its relationship with age and other related factors.Methods A total of 3733 women with twin pregnancy of 12-26⁺⁶ weeks who voluntarily underwent NIPT in the Ningbo Women and Children's Hospital from January 2018 to December 2022 were selected.The results of NIPT and amniocentesis were compared and all the participants were followed up.The detection rate of chromosomal abnormalities by NIPT was calculated,and its correlations with age,gestational weeks,chorionicity,and pregnancy type were analyzed.Results Among the 3733 cases,71 cases of fetal chromosome abnormality were indicated by NIPT,including 13 cases of trisomy 21,19 cases of trisomy 18,5 cases of trisomy 13,18 cases of sex chromosome abnormality,and 16 cases of chromosome microdeletion/duplication(excluding 21,18,13,and sex chromosomes),among which 34 cases were true positive and 37 cases were false positive.The overall sensitivity,specificity,and positive predictive value(PPV)of NIPT for chromosomal abnormalities in the cases of twin pregnancy were 100%,98.99%,and 47.89%(34/71),respectively.NIPT showed the sensitivity,specificity,and PPV of 100%,99.78%,and 78.38%(29/37)for trisomy 21,18,and 13,100%,99.56%,and 16.67%(3/18)for sex chromosome abnormalities,and 100%,99.62%,and 12.5%(2/16)for chromosome microdeletion/duplication,respectively.In the age group of ≥40 years,the NIPT for chromosomal abnormalities showed the PPV of 66.67%,the sensitivity of 100%,and the misdiagnosis rate of 30%。However,the NIPT for trisomy 21,18,and 13 showed the PPV of 100%,the misdiagnosis rate of 0,and the sensitivity and specificity of 100%.In terms of grouping based on gestational weeks,the NIPT for chromosomal abnormalities showed the highest PPV(51.28%)in the women with twin pregnancy for 14-17⁺⁶ weeks,followed by that(50.00%)in the women with twin pregnancy for 22-26⁺⁶ weeks;the NIPT for trisomy 21,18,and 13 showed the highest PPV of 94.74% in the gestation group of 14-17⁺⁶ weeks,followed by that(83.33%)in the gestation group of 18-21⁺⁶ weeks.The rate of dichorionic diamniotic twins was higher in assisted pregnancies than in natural pregnancies,and NIPT showed the same detection efficiency for dichorionic diamniotic twins and monochorionic diamniotic twins and the same detection efficiency for different pregnancy types.Conclusions NIPT has high accuracy in the diagnosis of twin pregnancy and high sensitivity and high specificity for different ages and gestational weeks,especially for trisomy 21,18,and 13.NIPT is suitable for assisted pregnancy and natural pregnancy,and it is of high value in clinical application.However,extensive application needs a large population-based study.
Pregnancy ; Child ; Female ; Humans ; Adult ; Down Syndrome/genetics* ; Pregnancy, Twin ; Prenatal Diagnosis ; Trisomy ; Chromosome Aberrations

OBJECTIVE: To assess the value of non-invasive prenatal testing (NIPT) for detecting fetal chromosomal microdeletion/microduplication syndromes by carrying out prenatal diagnoses for two fetuses with Xp22.31 microdeletion indicated by NIPT. METHODS: Two pregnant women suspected for fetal Xp22.31 microdeletion syndrome who presented at Zaozhuang Maternal and Child Health Care Hospital on December 5, 2017 and October 15, 2020 were selected as the study subjects. Clinical data of the two women were collected, and peripheral venous blood samples were collected for NIPT testing. Amniotic fluid samples were taken for G-banding chromosomal karyotyping analysis and copy number variation sequencing (CNV-seq) for fetus 1, while G-banding chromosomal karyotyping and single nucleotide polymorphism microarray analysis (SNP array) were carried out for fetus 2. Peripheral venous blood samples of couple 1 were collected for CNV-seq to verify the origin of copy number variation . RESULTS: NIPT indicated that fetus 1 had harbored a 1.3 Mb deletion in the Xp22.31 region, while G-banding chromosomal karyotyping had found no abnormality. CNV-seq analysis verified the fetus to be seg[GRCh37]del(X)(p22.31)chrX:g.6800001_7940000del, with a 1.14 Mb deletion at Xp22.31, which was derived from its mother. NIPT indicated that fetus 2 had harbored a 1.54 Mb deletion in the Xp22.31 region, while G-banding chromosomal karyotyping had found no abnormality. SNP array analysis indicated arr[GRCh37]Xp22.31(6458940_8003247)×0, with a 1.54 Mb deletion in Xp22.31 region. CONCLUSION NIPT not only has a good performance for detecting fetal trisomies 21, 18 and 13, but also has the potential for detecting chromosomal microdeletion/microduplications. For high risk fetuses indicated by NIPT, prenatal diagnosis needs to be carry out to verify the chromosomal abnormalities.
Child ; Female ; Pregnancy ; Humans ; DNA Copy Number Variations ; Prenatal Diagnosis ; Down Syndrome/diagnosis* ; Chromosome Aberrations ; Fetus

OBJECTIVE: To assess the value of non-invasive prenatal testing (NIPT) for trisomy 21 (T21), trisomy 18 (T18), trisomy 13 (T13), sex chromosome aneuploidies, chromosomal microdeletions and microduplications using cell-free fetal DNA from peripheral blood samples of pregnant women. METHODS: A total of 15 237 pregnant women who had undergone NIPT testing at the Maternity and Child Health Care Hospital of Zaozhuang from February 2015 to December 2021 were enrolled in this study. For those with a high risk by NIPT, amniotic fluid samples were collected for G-banding chromosomal karyotyping analysis and chromosomal microarray analysis to verify the consistency of NIPT with results of prenatal diagnosis. All of the women were followed up by telephone for pregnancy outcomes. RESULTS: Among the 15 237 pregnant women, 266 (1.75%) were detected with a high risk for fetal chromosomal abnormality were detected. Among these, 79 (29.7%) were at a high risk for T21, 26 (9.77%) were at a high risk for T18, 9 (3.38%) were at a high risk for T13, 74 (27.82%) were at a high risk for sex chromosome aneuploidies, 12 (4.51%) were at a high risk for other autosomal aneuploidies, and 66 (24.81%) were at a high risk for chromosomal microdeletions or microduplications. 217 women had accepted invasive prenatal diagnosis and respectively 50, 13, 1, 25, 1 and 18 were confirmed with T21, T18, T13, sex chromosome aneuploidies, autosomal aneuploidies and microdeletions/microduplications, and the positive predictive values were 75.76%, 68.42%, 11.11%, 40.32%, 10% and 35.29%, respectively. For 13 042 women (85.59%), the outcome of pregnancy were successfully followed up. During the follow-up, one false negative case of T21 was discovered. No false positive cases for T13 and T18 were found. CONCLUSION NIPT has a sound performance for screening T13, T18 and T21, and is also valuable for screening other autosomal aneuploidies, sex chromosome aneuploidies and chromosomal microdeletions/microduplications.
Child ; Female ; Pregnancy ; Humans ; Retrospective Studies ; Cell-Free Nucleic Acids ; Chromosome Disorders/genetics* ; Prenatal Diagnosis/methods* ; Down Syndrome/genetics* ; Sex Chromosome Aberrations ; Trisomy 18 Syndrome/genetics* ; Trisomy 13 Syndrome/diagnosis* ; Aneuploidy ; DNA/genetics* ; Trisomy/genetics*

OBJECTIVE: To assess the clinical efficacy and health economic value of non-invasive prenatal testing (NIPT) for the prenatal screening of common fetal chromosomal aneuploidies. METHODS: 10 612 pregnant women from October 2017 to December 2019 presented at the antenatal screening clinic of the General Hospital of Tianjin Medical University were selected as the study subjects. Results of NIPT and invasive prenatal diagnosis and follow-up outcome for the 10 612 pregnant women were retrospectively analyzed and compared. Meanwhile, NIPT data for two periods were analyzed for assessing the health economic value of NIPT as the second- or first-tier screening strategy for the prenatal diagnosis of fetal trisomies 21, 18 and 13. RESULTS: The NIPT was successful in 10 528 (99.72%) subjects, with the sensitivity for fetal trisomies 21, 18 and 13 being 100%, 92.86% and 100%, and the positive predictive value (PPV) being 89.74%, 61.90% and 44.44%, respectively. The PPV of NIPT for sex chromosome aneuploidies was 34.21%. Except for one false negative case of trisomy 18, the negative predictive value for trisomy 21, trisomy 13 and other chromosomal abnormalities were 100%. For pregnant women with high risk by serological screening, advanced maternal age or abnormal ultrasound soft markers, NIPT has yielded a significantly increased high risk ratio. There was no statistical difference in the PPV of NIPT among pregnant women from each subgroup. NIPT would have higher health economic value as a second-tier screening until 2019, while compared to 2015 ~ 2017, its incremental cost-effectiveness ratio as a first-tier screening had declined clearly. CONCLUSION The screening efficacy of NIPT for trisomies 21, 18 and 13 for a mixed population is significantly better than conventional serological screening, but it is relatively low for sex chromosomal abnormalities. NIPT can also be recommended for populations with relatively high risks along with detailed pre- and post-test genetic counselling. From the perspective of health economics, except for open neural tube defects, it is possible for NIPT to replace the conventional serological screening in the future as its cost continues to decrease.
Pregnancy ; Female ; Humans ; Trisomy/genetics* ; Retrospective Studies ; Prenatal Diagnosis/methods* ; Down Syndrome/genetics* ; Aneuploidy ; Chromosome Aberrations ; Trisomy 18 Syndrome/genetics* ; Sex Chromosome Aberrations ; Fetus

OBJECTIVE: To compare the clinical application and health economic values of non-invasive prenatal testing (NIPT) and second trimester serum screening (STSS). METHODS: A retrospective analysis was carried out on 54 026 singleton pregnant women undergoing NIPT and STSS from March 1, 2018 to December 31, 2019 in Changsha Maternal and Child Health Care Hospital. For pregnant women with high-risk results of NIPT, prenatal diagnosis and follow-up of pregnancy outcomes were conducted. The data was grouped to 4 screening models, and their cost-benefit was analyzed. RESULTS: The sensitivity, specificity and positive predictive value of NIPT were all higher than STSS. Screening models 1 to 4 have prevented the birth of 71, 29, 52 and 54 patients with Down syndrome, respectively. The safety index of screening models 1 to 4 were 0.0036, 0.3944, 02215 and 0.1281, respectively. When the price of NIPT was decreased to 600 RMB, the cost-benefit of the screening models 1 to 4 was 0.46, 0.65, 0.44 and 0.40 million RMB, respectively. CONCLUSION NIPT has a better detection performance than STSS. When the price of NIPT is 600 RMB, screening model 1 has the best screening effect and the highest accuracy, safety index and health economical value.
Child ; China ; Cost-Benefit Analysis ; Down Syndrome/diagnosis* ; Female ; Humans ; Pregnancy ; Prenatal Diagnosis/methods* ; Retrospective Studies

OBJECTIVE: To assess the diagnostic value of copy number variation sequencing (CNV-seq) in the genetic etiology of fetuses with nasal bone dysplasia (NBD). METHODS: A total of 217 fetuses discovered with NBD from December 2017 to December 2020 were divided into the isolated NBD group and NBD combined with other anomalies group, for which copy number variations (CNVs) were analyzed. RESULTS: A total of 40 fetal abnormalities were detected in 217 cases, with an overall abnormal rate of 18.4%. These included 31 cases with aneuploidies (14.3%, 31/217) and 9 cases with genomic CNVs (4.1%, 9/217). Five cases of trisomy 21 (3.5%, 5/144) and two CNVs cases with unknown clinical significance (1.4%, 2/144) were detected in the isolated group. As for the combined NBD group, 26 aneuploidies (35.6%, 26/73), including 19 cases with trisomy 21, 6 cases with trisomy 18, 1 case with trisomy 13, 5 cases with pathogenic CNVs (6.8%, 5/73), and 2 cases with CNVs of unknown clinical significance (2.7%, 2/73) were detected. A significant difference was detected between the two groups (P < 0.01). CONCLUSION The detection rate of CNV-seq is high for chromosomal aneuploidies and pathogenic CNVs in fetuses with NBD, particularly in those combined with other ultrasonic abnormalities.
Aneuploidy ; Bone Diseases, Developmental ; Chromosome Aberrations ; DNA Copy Number Variations ; Down Syndrome/genetics* ; Female ; Fetus/abnormalities* ; Humans ; Pregnancy ; Prenatal Diagnosis ; Trisomy

OBJECTIVE: To analyze the Z values of true and false positive cases by non-invasive prenatal testing (NIPT) in order to improve its accuracy in clinical practice. METHODS: Results of 24 384 NIPT tests were reviewed. For cases with high risks for trisomies 21, 18 and 13, the range of Z values in true and false positive cases was analyzed and discussed. RESULTS: A total of 335 high-risk cases were identified by NIPT, among which 256 had elected prenatal diagnosis, 153 (59.77%) were verified as true positives, and 103 (40.23%) were false positives, and the area under the curve (AUC) was 0.9994. For NIPT screening, the positive predictive value (PPV) for trisomy 21 was 100% when Z>13, regardless if the pregnant woman was over 35. When 335 and about 41.6% (5/12) for those<35. For trisomy 18, the PPV was 100% when Z>13, and only 14.3% (1/7) when 3CONCLUSION NIPT is a technique similar to prenatal diagnosis and has a high positive predictive value for trisomies 18 and 21. Proper classification and division of the high-risk Z value of NIPT can further improve the positive predictive values for trisomies 21, 18 and 13 in different intervals, and is more helpful to guide clinicians in genetic counseling for high-risk pregnant women. Meanwhile, the compliance of prenatal diagnosis in high risk NIPT pregnant women with Z value between 3~13 was improved.
Female ; Pregnancy ; Humans ; Trisomy 13 Syndrome/genetics* ; Trisomy/genetics* ; Down Syndrome/genetics* ; Chromosome Disorders/genetics* ; Trisomy 18 Syndrome/diagnosis* ; Prenatal Diagnosis/methods*

OBJECTIVE: To prepare a quality control sample for non-invasive prenatal screening (NIPS) and evaluate its quality and stability. METHODS: According to the biological characteristics of cell-free fetal DNA derived from the plasma of pregnant women, the simulated samples were prepared by mixing genomic DNA fragments derived from individuals with trisomy 21, trisomy 18 and trisomy 13 and background plasma. The samples were then compared with commercially made quality control products tested on various NIPS platforms and stored at -80℃, -20℃, 4℃, 24℃ and 37℃ for various periods of time. RESULTS: The simulated samples have attained the expected results and could be detected on various platforms and stored at -80℃and -20℃ for at least 30 days. CONCLUSION A simulated sample was successfully prepared and possessed good stability. It can be used as the quality control sample for NIPS.
Aneuploidy ; Down Syndrome/genetics* ; Female ; Humans ; Noninvasive Prenatal Testing ; Pregnancy ; Prenatal Diagnosis ; Trisomy/genetics*

OBJECTIVE: To investigate the clinical effect of expanded non-invasive prenatal testing (NIPT-plus) for serological screening of fetuses with high-risk for Down's syndrome. METHODS: To retrospectively study the screening results, prenatal diagnosis and pregnancy outcomes of 1561 midterm pregnant women underwent NIPT-plus in our center from September 2018 to December 2019 due to serological screening with high-risk for Down's syndrome(≥ 1/270). RESULTS: 45 pregnant women had a high-risk with a detection rate of 2.88% (45/1561) of 1561 pregnant women who performed NIPT-plus. 40 pregnant women underwent invasive prenatal diagnosis and 20 cases were confirmed with a positive predictive value of 50.0% (20/40). Statistical analysis showed that NIPT-plus has a high detection rate for trisomy 21, sex chromosomal aneuploidy, and MMS in the 0.1/90 group, but with a positive predictive value lower than the other two groups. CONCLUSION The detection rate and PPVs of NIPT-plus in different groups of Down's high-risk pregnant women was different. NIPT-plus can reduce the pressure of prenatal diagnosis and can be used as a screening method for Down's syndrome with high risk in pregnant women.
Down Syndrome/genetics* ; Female ; Fetus ; Humans ; Pregnancy ; Prenatal Diagnosis ; Retrospective Studies ; Trisomy

OBJECTIVE: To assess the clinical value of non-invasive prenatal testing (NIPT) for the screening of trisomy and copy number variations (CNVs) of chromosomes 21, 18 and 13. METHODS: From January 2015 to December 2019, 40 628 pregnant women underwent NIPT testing using high-throughput sequencing and bioinformatics analysis to test the cell-free fetal DNA in maternal plasma. High-risk pregnant women underwent invasive prenatal diagnosis, while low-risk ones were followed up by telephone. RESULTS: The three most common indications included intermediate risk of serological screening, high risk of serological screening and advanced maternal age. Among all pregnant women, 257 cases were detected as trisomy 21, 18 and 13 (170, 49 and 38 cases, respectively). 227 cases chose invasive prenatal diagnosis, with respectively 122, 28 and 10 cases confirmed. The positive predictive value (PPV) was 81.33% (122/150), 65.12% (28/43), 29.41% (10/34), respectively. Two false negative cases of trisomy 18 were found during follow-up. Meanwhile, NIPT has detected 46 cases (15, 16 and 15 cases, respectively) CNVs on chromosomes 21, 18 and 13, among which 37 cases underwent invasive prenatal diagnosis. There were 5, 3 and 5 positive cases, which yielded a PPV of 41.67% (5/12), 25%(3/12) and 33.33%(5/15), respectively. Two other chromosome CNVs were accidentally discovered among the false positive samples. CONCLUSION The incidence of chromosomal abnormalities in the serological screening high-risk group was 52.02%, which was significantly higher than other groups. NIPT has a high sensitivity and specificity for the screening of trisomies 21, 18 and 13, while its accuracy for detecting CNVs of chromosomes 21, 18 and 13 needs to be improved. As a screening method, NIPT has a great clinical value, though there are still limitations of false positive and false negative results.Comprehensive pre- and post-test genetic counseling should be provided to the patients.
Aneuploidy ; Chromosome Disorders/genetics* ; Chromosomes ; DNA Copy Number Variations ; Down Syndrome/genetics* ; Female ; Humans ; Pregnancy ; Prenatal Diagnosis ; Trisomy/genetics* ; Trisomy 18 Syndrome/genetics*