OBJECTIVE: The aim of this study was to examine whether there is a correlation between different types of ventricular septal defects (VSD) and chromosomal abnormalities in the low-risk setting of non-invasive prenatal testing (NIPT) and to evaluate the prognosis of fetuses with varying types of VSD.
METHODS: Cases of pregnant women who underwent amniocentesis due to fetal VSD were collected by Tianjin Central Hospital of Obstetrics and Gynecology from May 2017 to May 2022. Exclusions were made for those without NIPT, with high-risk NIPT results, genetic disorders, and those lost to follow-up. Data collected included ultrasound classification of VSD, prenatal NIPT results, copy-number variations (CNVs) results, and neonatal outcomes.
RESULTS: The prevalence of pathogenic CNVs was investigated in 74 cases of VSDs. Of these cases, 45 were isolated VSDs (9 muscular and 36 non-muscular) and 29 were non-isolated VSDs (10 with intracardiac and 19 with extra-cardiac structural anomalies). The results revealed that the incidence of pathogenic CNVs was lower in isolated VSDs compared to non-isolated VSDs in a low-risk NIPT condition (χ2 = 9.344, P = 0.002). There was no significant difference in the prevalence of pathogenic CNVs between VSDs with intracardiac and extra-cardiac structural anomalies (P = 0.541). Moreover, VSDs associated with intracardiac structural anomalies had the highest rate of surgical intervention.
CONCLUSIONS: When NIPT is low-risk and VSD is isolated, the likelihood of fetal chromosomal defects is not increased. However, if there are intra- or extra-cardiac structural abnormalities present alongside VSD, the possibility of pathogenic CNV is considerably greater, necessitating invasive prenatal diagnosis. Isolated muscular VSDs usually do not require surgery, which can be used as a basis for prenatal counseling regarding fetal VSD.

Background: Paternal uniparental disomy (UPD) of chromosome 7 is extremely rare, and only a few postnatal cases have been reported. The effects on growth were discordant in these cases, and the relevance of paternal UPD(7) to growth caused by imprinting remains questionable. Case presentation: Here, we report a prenatal case that underwent invasive prenatal diagnosis due to the high risk of Down\'s syndrome and failed noninvasive prenatal screening. The fetus had a normal karyotype and no apparent copy number variation. Homozygous copy-neutral regions on chromosome 7 were identified using a single nucleotide polymorphism (SNP) array; the data for the parent-child trios showed that the fetus carried the whole paternal isodisomy of chromosome 7. Whole exome and Sanger sequencing revealed a homozygous frameshift mutation in SUGCT at 7p14.1, from the heterozygous carrier father, with no contribution from the mother. The parents decided to continue with the pregnancy after genetic counseling, and the neonate had normal physical findings at birth and showed overweight after birth during a long-term intensive follow-up. Conclusion: We report the first prenatal case who carried paternal UPD(7) and homozygous SUGCT mutation with an overweight phenotype after birth. The overweight may be caused by paternal UPD(7) or homozygous frameshift mutation of SUGCT, or both of them, but it is unclear which contributes more.

BACKGROUND: Standard noninvasive prenatal screening(NIPS) is an accurate and reliable method to screen for common chromosome aneuploidies, such as trisomy 21, 18 and 13. Extended NIPS has been used in clinic for not only aneuploidies but also copy number variants(CNVs). Here we aim to define the range of chromosomal abnormalities that should be able to identify by NIPS in order to be an efficient extended screening test for chromosomal abnormalities.
METHODS: A prospective study was conducted, involving pregnant women without fetal sonographic structural abnormalities who underwent amniocentesis. Prenatal samples were analyzed using copy number variation sequencing(CNV-seq) to identify fetal chromosomal abnormalities.
RESULTS: Of 28,469 pregnancies included 1,022 (3.59%) were identified with clinically significant fetal chromosome abnormalities, including 587 aneuploidies (2.06%) and 435 (1.53%) pathogenic (P) / likely pathogenic (LP) CNVs. P/LP CNVs were found in all chromosomes, but the distribution was not uniform. Among them, P/LP CNVs in chromosomes 16, 22, and X exhibited the highest frequencies. In addition, P/LP CNVs were most common on distal ends of the chromosomes and in low copy repeat regions. Recurrent microdeletion/microduplication syndromes (MMS) accounted for 40.69% of total P/LP CNVs. The size of most P/LP CNVs (77.47%) was < 3 Mb.
CONCLUSIONS: In addition to aneuploidies, the scope of extended NIPS should include the currently known P/LP CNVs, especially the regions with recurrent MMS loci, distal ends of the chromosomes, and low copy repeat regions. To be effective detection should include CNVs of < 3 Mb. Meanwhile, sufficient preclinical validation is still needed to ensure the clinical effect of extended NIPS.

We report on the case of prenatal detection of trisomy 2 in placental biopsy and further algorithm of genetic counseling and testing. A 29-year-old woman with first-trimester biochemical markers refused chorionic villus sampling and preferred targeted non-invasive prenatal testing (NIPT), which showed low risk for aneuploidies 13, 18, 21, and X. A series of ultrasound examinations revealed increased chorion thickness at 13/14 weeks of gestation and fetal growth retardation, a hyperechoic bowel, challenging visualization of the kidneys, dolichocephaly, ventriculomegaly, increase in placental thickness, and pronounced oligohydramnios at 16/17 weeks of gestation. The patient was referred to our center for an invasive prenatal diagnosis. The patient\'s blood and placenta were sampled for whole-genome sequencing-based NIPT and array comparative genomic hybridization (aCGH), respectively. Both investigations revealed trisomy 2. Further prenatal genetic testing in order to confirm trisomy 2 in amniocytes and/or fetal blood was highly questionable because oligohydramnios and fetal growth retardation made amniocentesis and cordocentesis technically unfeasible. The patient opted to terminate the pregnancy. Pathological examination of the fetus revealed internal hydrocephalus, atrophy of brain structure, and craniofacial dysmorphism. Conventional cytogenetic analysis and fluorescence in situ hybridization revealed chromosome 2 mosaicism with a prevalence of trisomic clone in the placenta (83.2% vs. 16.8%) and a low frequency of trisomy 2, which did not exceed 0.6% in fetal tissues, advocating for low-level true fetal mosaicism. To conclude, in pregnancies at risk of fetal chromosomal abnormalities that refuse invasive prenatal diagnosis, whole-genome sequencing-based NIPT, but not targeted NIPT, should be considered. In prenatal cases of trisomy 2, true mosaicism should be distinguished from placental-confined mosaicism using cytogenetic analysis of amniotic fluid cells or fetal blood cells. However, if material sampling is impossible due to oligohydramnios and/or fetal growth retardation, further decisions should be based on a series of high-resolution fetal ultrasound examinations. Genetic counseling for the risk of uniparental disomy in a fetus is also required.

UNASSIGNED: To evaluate the clinical efficiency of noninvasive prenatal testing (NIPT) for fetal chromosomal aneuploidy screening in twin pregnancies.
UNASSIGNED: A total of 1650 women with twin pregnancies were enrolled in the study, which underwent NIPT at the Southwest Hospital, Army Medical University, Chongqing, China from January 2013 to June 2022. Fetal karyotyping analysis was conducted in high-risk patients, with subsequent follow-up on pregnancy outcomes.
UNASSIGNED: In 1650 pregnancies, NIPT results showed ten cases of the fetal chromosome aneuploidy, of which six cases were true positive and four cases were false positive. The sensitivity, specificity, positive predictive value (PPV), and false-positive rate (FPR) of trisomy 21 were 100%, 99.79%, 57.14%, and 0.18%, respectively. Sensitivity, specificity, PPV, and FPR of trisomy 18 were 100%, 99.94%, 50%, and 0.06%, respectively. The sensitivity, specificity, PPV, and FPR of trisomy 13 were 100%, 100%, 100%, and 0%, respectively. No false negatives were detected and the negative predictive value (NPV) was 100% of the total. Eleven pregnancies failed the NIPT test with no-call due to the low fetal fraction (< 4%).
UNASSIGNED: NIPT is a high-performing routine primary prenatal screening test in twin pregnancies, with high sensitivity and specificity in screening for fetal aneuploidy.

This study explored the diagnostic efficiency of different prenatal diagnostic approaches for women with positive non-invasive prenatal screening (NIPS) results by analyzing their clinical information and pregnancy outcomes. We collected data on 626 NIPS-positive pregnant women from January 2017 to June 2021 and arranged subsequent prenatal diagnostic operations for them after genetic counseling, along with long-term intensive follow-up. A total of 567 women accepted invasive prenatal diagnosis (IPD) (90.58%), and 262 cases were confirmed as true positives for NIPS. The positive predictive values for trisomies 21 (T21), 18 (T18), and 13 (T13); sex chromosome aneuploidies (SCAs); rare autosomal trisomies (RATs); and microdeletion and microduplication syndromes (MMS) were 81.13%, 37.93%, 18.42%, 48.83%, 18.37%, and 41.67%, respectively. Discordant results between NIPS and IPD were observed in 48 cases, with the discordance rate being 8.47%. Additionally, there were 43 cases with discordant results between karyotyping and chromosomal microarray analysis (CMA)/copy number variation sequencing. Additional reporting of RATs and MMS with routine NIPS that only detects T21/T18/T13 and SCAs can yield more accurate diagnoses. However, NIPS cannot be used as a substitute for IPD owing to its high false positive rate and discordance with other diagnostic methods. Therefore, we recommend CMA combined with karyotyping as the preferred method for accurately diagnosing NIPS-positive women.

Increased fetal nuchal translucency (NT) is a common ultrasonic manifestation during pregnancy. Many studies have confirmed that NT ≥ 3 mm is a high risk factor for adverse pregnancy outcome. However, when NT is between 2.5 and 2.9 mm, will it increase the risk of fetal chromosome abnormalities and other diseases? What is the most appropriate method for prenatal chromosome evaluation? At present, it has not been widely reported in the literature, and the conclusion is also controversial. This prospective cohort study included fetal samples from women who underwent amniocentesis from 2017 to 2020. The samples of the experimental group were fetuses with NT ≥ 2.5 mm at 11 to 13 + 6 weeks of gestation, with or without ultrasonographic anomaly. The control group contained fetal NT < 2.5 mm without ultrasonographic anomalies. All amniotic fluid samples were tested by copy number variants sequencing. In 262 fetal samples with isolated NT from 2.5 to 2.9 mm, the detection rate of aneuploidy was 3.4% (9/262), and the risk of aneuploidy was significantly higher than that of the control group (1.4%, 32/2331) (relative risk 2.5, 95% CI 1.2-5.2). The detection rates of other pathogenic/likely pathogenic copy number variants in the two groups were 0.8% (2/262) and 1.3% (31/2331), respectively, which was not statistically significant (relative risk 0.6, 95% CI 0.1-2.4). Our results showed that isolated NT from 2.5 to 2.9 mm increased the risk of fetal chromosome aneuploidy. Therefore, noninvasive prenatal screening is recommended as the first choice for prenatal chromosome evaluation in this population.

BACKGROUND: The broad application of high-resolution chromosome detection technology in prenatal diagnosis has identified copy number loss (CNL) involving autosomal dominant (AD) genes in certain fetuses. Exon sequencing of fetuses exhibiting structural anomalies yields diagnostic information in up to 20% of cases. However, there is currently no relevant literature about the genetic origin and pregnancy outcome of CNL involving AD genes in fetuses without structural abnormalities.
RESULTS: This was a prospective study involving pregnant women who underwent amniocentesis for fetal copy number variation sequencing (CNVseq). Detection of parent-of-origin was suggested in cases of samples with CNL involving AD genes and the pregnancy outcome was monitored. Amniotic fluid samples from 24,844 fetuses without structural abnormalities were successfully tested via CNVseq. The results showed that 134 fetuses (0.5%) had small CNL (< 10 Mb) containing AD genes, after excluding microdeletion and microduplication syndrome and polymorphisms. By monitoring the pregnancy outcomes of the 134 fetuses, we found that 104 (77.6%) were good, 13 (9.7%) were adverse, and 17 (12.7%) pregnant women voluntarily chose to terminate pregnancy. Of the 13 fetuses with adverse pregnancy outcomes, only 2 fetuses had phenotypes consistent with those of diseases caused by AD genes involved in CNL.
CONCLUSIONS: The overall prognosis for fetuses without family history or structural abnormalities but with small CNL containing AD genes detected during pregnancy is good. The genetic origin, overlap status of established haploinsufficient gene and/or region, size of the CNL, and genetic mode may affect the pathogenicity of the CNL.

BACKGROUND: Increased nuchal translucency (NT) is closely related to an increased risk of chromosomal abnormalities. However, the criterion of increased NT for invasive prenatal diagnosis remains controversial, as the cutoff values are inconsistent among countries. This study was conducted to compare the various cutoff values of increased NT and calculate the incidence of chromosomal abnormalities to determine the predictive ability of these cutoff values in conventional chromosome analysis.
METHODS: A total of 3223 invasive samples with increased nuchal translucency (NT) or other non-ultrasound indications were collected from singleton pregnant women. Samples with isolated increased NT were divided into five groups based on the NT thickness: 909 samples in the NT ≥2.5 mm group, 819 samples in the NT ≥95th group, 547 samples in the NT ≥99th group, 527 samples in the NT ≥3.0 mm group, and 253 samples in the NT ≥3.5 mm group; 2301 samples with normal NT were considered as the control group. All five groups were karyotyped and the results were compared. The accuracy of the NT cutoff value for the screening of chromosomal abnormalities was assessed using receiver operating characteristic curve analysis.
RESULTS: Detection of all chromosomal aberrations and trisomy 21 showed that the sensitivity and false-positive rate decreased sequentially in the NT ≥2.5 mm, NT ≥95th, NT ≥3 mm, NT ≥99th, and NT ≥3.5 mm groups, whereas the specificity, positive predictive value, and false-negative rates increased sequentially. Comprehensive analysis of various factors, including sensitivity and specificity, revealed values equal to or higher than the calculated 95th percentile of NT distribution, which showed a sensitivity of 49.2% and specificity of 75.67% for detecting all aneuploidies and a sensitivity of 64% and specificity of 75.45% for trisomy 21, exhibiting the highest ability for the screening of chromosomal defects in first-trimester screening.
CONCLUSIONS: For different thresholds of NT thickness, values equal to or higher than the calculated 95th percentile of the NT distribution showed the highest ability for the screening of chromosomal defects in first-trimester screening.

In the age of noninvasive prenatal testing, there is still an important role for invasive prenatal diagnosis, even for chromosomes 13, 18, and 21.