Prenatal diagnosis indications and pregnancy outcomes and its impact factors in 1 372 pregnant women with fetal sex chromosome aneuploidy / 中华围产医学杂志

Objective:To analyze the indications for prenatal diagnosis and summarize the pregnancy outcomes and its influencing factors of pregnant women with fetal sex chromosome aneuploidy (SCA).Methods:This study retrospectively enrolled 1 372 fetuses prenatally diagnosed with SCA in Medical Genetics Center of Guangdong Women and Children Hospital from January 2013 to December 2021. The relationship between prenatal diagnosis indications and SCA as well as between ultrasound abnormalities, pregnancy outcomes and SCA types were analyzed by Chi-square test and trend Chi-square test. Results:The most common prenatal diagnosis indication was abnormal non-invasive prenatal testing (NIPT) (61.6%, 845/1 372). The most common SCA type was 47,XXY in cases with indications of abnormal NIPT and advanced maternal age, mosaic in cases with high or borderline risk of Down syndrome, and 45,X in cases with increased nuchal translucency or cystic hygroma. Of 1 372 pregnant women with fetal SCA, 17 were lost to follow-up, seven had intrauterine fetal death, and 1 348 (98.3%) were followed up for pregnancy outcomes including 36.3% (489/1 348) continued pregnancies and 63.7% (859/1 348) terminations. Pregnancy termination rates decreased sequentially in pregnant women carrying fetuses with 45,X, 47,XXY, mosaic, 47,XXX and 47,XYY [99.2% (247/249), 74.5% (307/412), 67.8% (156/230), 36.6% (86/235) and 28.4% (63/222), χ2trend=352.76, P<0.001]. There was no significant difference in pregnancy termination rates among the cases with different mosaic mutations (all P>0.05). The pregnancy termination rate was higher in fetuses with SCA complicated by ultrasound structural abnormalities than in those without ultrasound abnormalities and those with ultrasound soft markers [91.5% (182/199) vs 57.1% (535/937) and 67.0% (142/212), χ2 were 83.68 and 36.85, both P<0.001]. Moreover, the pregnancy termination rate in fetuses with SCA complicated by ultrasound soft markers was higher than those without ultrasound abnormalities ( χ2=7.13, P<0.05). Conclusions:NIPT abnormality is the most common indication for prenatal diagnosis of SCA. The types of SCA and ultrasound findings are important factors determining whether the pregnancy would be continued or not.

Consensus on technological standards for non-invasive prenatal screening of pathogenic copy number variations by high-throughput sequencing of maternal plasma cell-free DNA / 中华医学遗传学杂志

Genomic disorders caused by pathogenic copy number variation (pCNV) have proven to underlie a significant proportion of birth defects. With technological advance, improvement of bioinformatics analysis procedure, and accumulation of clinical data, non-invasive prenatal screening of pCNV (NIPS-pCNV) by high-throughput sequencing of maternal plasma cell-free DNA has been put to use in clinical settings. Specialized standards for clinical application of NIPS-pCNV are required. Based on the discussion, 10 pCNV-associated diseases with well-defined conditions and 5 common chromosomal aneuploidy syndromes are recommended as the target of screening in this consensus. Meanwhile, a standardized procedure for NIPS-pCNV is also provided, which may facilitate propagation of this technique in clinical settings.

Analysis of the results of chromosomal trisomies 21, 18 and 13 screening among 40 628 women by non-invasive prenatal testing / 中华医学遗传学杂志

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.

The value of noninvasive prenatal screening for the detection of fetal chromosome 16 aneuploidy / 中华医学遗传学杂志

OBJECTIVE@#To assess the value of non-invasive prenatal screening (NIPS) for the detection of fetal chromosome 16 aneuploidy through multi-method verification and follow-up of pregnancy outcomes.@*METHODS@#From January 2016 to December 2017, 7972 pregnant women with singleton pregnancies accepted the NIPS test after 10th gestational week with informed consent. Those with fetal chromosome 16 abnormality suggestive by the NIPS test were subjected to prenatal diagnosis including chromosomal karyotyping and chromosomal microarray analysis (CMA).@*RESULTS@#Of the 7972 pregnant women tested by NIPS, 16 (0.2%) were predicted to have fetal chromosome 16 abnormality. The average age of the 16 pregnant women was 33.5 ± 5.24, and the average gestational week was 19.88±2.47. Chromosomal karyotyping verified that 3 fetuses had mosaicisms and 1 carried pericentric inversion of chromosome 9, which yielded a positive predictive value (PPV) of 18.8%. CMA has detected 7 fetuses with genomic abnormalities, which yielded a PPV of 43.8%. Eleven of the 16 women (68.8%) have given birth to healthy babies.@*CONCLUSION@#For pregnant women with a high risk of chromosome 16 aneuploidy suggested by NIPS, the prognosis of fetus should be evaluated by multiple methods. Compared with conventional karyotyping analysis, molecular methods such as CMA are far superior.

Detection of copy number variations for chromosome non-numerical abnormality with non-invasive prenatal testing: clinical analysis of 205 cases / 中华围产医学杂志

Objective:To evaluate the clinical value of non-invasive prenatal testing (NIPT) in detecting copy number variations (CNVs).Methods:There were 37 845 pregnant women undergoing NIPT in Guangdong Women and Children Hospital from January 1, 2015 to September 1, 2018, of which 205 with CNVs were detected in addition to chromosome numerical abnormality and retrospectively analyzed. Among the 205 cases, 137 received invasive prenatal diagnosis. Pregnant outcomes were followed up and the efficiency of NIPT in detecting CNVs was analyzed by descriptive statistical analysis.Results:The detection rate of NIPT for CNVs was 0.54% (205/37 845). Among the 137 cases undergoing invasive prenatal diagnosis, 110 showed normal karyotype, 27 with abnormal including two having CNVs that were inconsistent with NIPT findings and 25 with consistent results. The positive predictive value, sensitivity and specificity of NIPT for CNVs were 18.2%(25/137), 100.0%(25/25) and 99.7%(37 625/37 737), respectively. Among the 27 pregnant women with positive findings in prenatal diagnosis, five were lost to follow-up; eight terminated their pregnancies; 14 gave birth to alive baby with normal phenotype. While among the 110 pregnant women with negative results in prenatal diagnosis, 87 delivered full-term neonates including two having patent foramen ovale and 85 with normal phenotype; three gave birth prematurely; one terminated pregnancy at 28 +2 gestational weeks due to preeclampsia; two had inevitable abortion; two requested termination and 15 were lost to follow-up. Conclusions:Routine NIPT has high performance in screening CNVs but those pregnant women with positive NIPT results should be counseled after referring to their invasive prenatal diagnosis results, ultrasound scan and clinical information.

Application of non-invasive prenatal genetic testing in prenatal anomaly index screening / 中华检验医学杂志

Objective@#To evaluate the value of non-invasive prenatal testing (NIPT) in pregnancies with anomaly in prenatal screening. @*Methods@#This was a retrospective study of 2 837 singleton pregnancies who performed NIPT indicated by isolated anomaly in prenatal screening at Guangdong Women and Children Hospital between November 2014 and August 2016. All pregnancies were divided into 3 groups by single indication: advanced maternal age ( AMA, ≥35), abnormal multiples of the median (MoM) in standard screening, increased nuchal translucency thickness (NT, 2.5-3.0 mm). High risk results were verified by prenatal diagnosis. Low risk cases were followed by a 22-26 week anatomical ultrasound examination. All of the cases were followed up and the performance of NIPT for every single indication was evaluated. @*Results@#There were total of 2 837 pregnant women who underwent NIPT. Twenty-five of 2 448 pregnancies indicated by AMA had high risk results, among which 17 were confirmed by invasive genetic testing, except 1 case rejecting prenatal diagnosis. In 351 pregnant women with abnormal MoM, NIPT found 3 cases of sex chromosome aneuploidies (SCA) and 2 of them were validated by invasive prenatal diagnosis. Increased NT group included 38 cases, NIPT found 1 case of trisomy 21 which was consistent with karyotype analysis. For common aneuploidies and SCA, the performance of NIPT in the pregnant women who indicated by AMA, abnormal MoM and increased NT were as the follows: the sensitivity were 17/17, 2/2 and 1/1 respectively, the specificity were 99.7% (2 423/2 431), 99.7% (348/349) and 100%(37/37), the positive predictive value were 68% (17/25), 2/3 and 1/1, the negative predictive value were 100% (2 423/2 423), 100% (348/348) and 100% (38/38), respectively. By follow-up survey, a total of 8 cases of abnormal fetus were recorded in NIPT low-risk women, including 5 cases of termination of pregnancy due to abnormal ultrasound findings, 2 cases of abortion as a result of severe obstetric complications and 1 case of stillbirth. @*Conclusions@#To the pregnant women who indicated by advanced maternal age, abnormal MoM and increased NT (2.5-3.0 mm), NIPT had satisfactory performance for common aneuploidies, and also had potential value for SCA, resulting in a significant reduction in diagnostic procedures. However, for NIPT low-risk pregnancies, routine antenatal examination and anatomical ultrasound detection would be highly necessary to avoid missing abnormal fetuses.(Chin J Lab Med, 2018, 41: 509-513)