Prenatal diagnosis and pregnancy outcome analysis of thickened nuchal fold in the second trimester

Chromosome microarray analysis combined with karyotype analysis is a powerful tool for the detection in pregnant women with high-risk indicators

BACKGROUND

Karyotype analysis and fluorescence in situ hybridization (FISH) are commonly used for prenatal diagnosis, however they have many disadvantages. Chromosome microarray analysis (CMA) has the potential to overcome these disadvantages. This study aimed to evaluate the clinical value of CMA in the diagnosis of fetal chromosomal anomalies in southwest of China.

METHODS

A total of 3336 samples of amniotic fluid or umbilical cord blood from pregnant women with high-risk indicators at our center in southwest of China from June 2018 to January 2023 were included in the retrospective analysis. 3222 cases tested by CMA and karyotyping, 114 cases only tested by CMA.

RESULTS

3336 samples divided into 2911 cases with single and 425 cases with multiple high-risk indicators. The aneuploidy and pathogenic/likely pathogenic copy number variations (CNVs) of 2911 cases with single high-risk indicator were 4.43% (129/2911) and 2.44% (71/2911) respectively; the aneuploidy and pathogenic/likely pathogenic CNVs of 425 cases with multiple high-risk indicators were 6.82% (29/425) and 2.12% (9/425) respectively. The rate of aneuploidy increased significantly with pregnancy age or NT value. The detection rate of aneuploidy on cases with AMA combined NT ≥ 2.5 mm was significantly higher than that in cases only with AMA (p < 0.001); the detection rate of aneuploidy and pathogenic/likely pathogenic CNVs in cases with AMA combined NIPT high-risk were higher than that in cases only with AMA (p < 0.001, p < 0.05).

CONCLUSIONS

The combined application of CMA and karyotyping were recommended in prenatal diagnosis for providing a scientific and accurate genetic diagnosis and improving the quality of prenatal genetic counseling.

Perinatal outcomes and genomic characteristics of fetal copy number variants: An individual record linkage study of 713 pregnancies

OBJECTIVE

To determine the perinatal outcomes of fetuses diagnosed with a pathogenic copy number variant (CNV) or variant of uncertain significance (VUS); and to characterize these variants in terms of testing indication, genomic location, size, and inheritance.

METHODS

Retrospective study of singleton pregnancies with a pathogenic CNV or VUS from a single laboratory during 2012-2018. Probabilistic record linkage between the prenatal diagnosis dataset and perinatal outcome data for births from 20 weeks gestation was performed. If no birth record was found, this implied a pregnancy loss <20 weeks.

RESULTS

We included 6945 prenatal microarray results; a pathogenic CNV was detected in 230 (3.3%, 95% CI: 2.9%-3.8%) and a VUS in 483 (7.0%, 95% CI: 6.4%-7.6%). Of pregnancies with a pathogenic CNV, 20.0% (95% CI: 15.3%-25.6%) had a live birth, 3.0% (95% CI: 1.5%-6.2%) had a perinatal death (stillbirth or neonatal death), and 77% (95% CI: 71.1%-81.9%) had no birth record. Of those with a VUS, 64.4% (95% CI: 60.0%-68.5%) had a live birth, 1.8% (95% CI: 1.0%-3.5%) had a perinatal death, and no birth record was found for 33.7% (95% CI: 29.7%-38.1%). Most pathogenic CNVs (61.1%) were <7 Mb in size. The most common microdeletion syndromes were DiGeorge, Wolf-Hirschhorn, and Cri-du-chat syndromes.

CONCLUSION

This study provides an overview of perinatal outcomes and frequency of recurrent CNVs observed in the prenatal microarray era.

Prenatal diagnosis of ultrasound soft markers in a single medical center of mainland China

BACKGROUND

There are a few studies on the chromosomal aberration of Ultrasound soft markers (USMs). The aim of this study was to determine the detection rate of clinically significant chromosomal abnormalities (CSCA) in fetuses with different USMs.

METHODS

This study included fetuses with USMs who underwent invasive prenatal diagnosis for karyotype and/or chromosomal microarray (CMA) by categorizing into two groups: a single USM (SUSM) and multiple USMs (MUSMs).

RESULTS

Of the 358 cases with USMs, CSCA occurred in 3.09% (8/259) and 8.08% (8/99) of the SUSM and MUSM groups, respectively (P < 0.05). Of 16 cases identified with CSCA, theoretically 68.75% (11/16) could be detected by karyotype, while 31.25% (5/16) could be recognized only by CMA. Among CSCA cases, the most frequent USM was an absent or hypoplastic nasal bone (62.5%, 10/16). In cases with negative karyotypes and/or CMA, follow-up results were available in 307 cases, including 292 term deliveries, 6 preterm deliveries, 8 terminations of pregnancy due to USMs, and 1 still birth.

CONCLUSION

MUSMs increased the risk of chromosomal abnormalities. An absent or hypoplastic nasal bone was the most clinically significant marker either alone or in combination with other USMs. Most of SUSM had a good prognosis.

Genetic examination for fetuses with increased nuchal translucency by exome sequencing

AIM

This retrospective study aimed to investigate the value of exome sequencing (ES) in fetuses with isolated first-trimester increased nuchal translucency (NT) and normal chromosomes.

METHODS

ES was performed on 103 fetuses with isolated first trimester increased NT and normal chromosomes. The detection rate of monogenic conditions was analyzed.

RESULTS

Diagnostic variants were detected in nine cases in which phenotypes and genotypes correlated well, two positive cases were Thanatophoric dysplasia type I, and one case was Kabuki syndrome, which had been detected in previous studies. Eight of the nine cases with diagnostic variants developed additional structural malformations later in pregnancy. Among the nine positive cases, six had a NT thickness between 95th percentile (95th-3.4 mm), and three cases with an increased NT of 3.5 mm or greater. Also, there was no statistical difference in the diagnosis of diagnostic variants in cases with or without a thickened nuchal fold (NF).

CONCLUSIONS

The diagnostic yield of prenatal ES is low for fetuses with an isolated increased NT. In addition to Noonan syndrome, there are additional genetic syndromes such as Kabuki syndrome and Thanatophoric dysplasia type I that are potentially associated with an increased NT. A cut-off of greater than the 95th percentile may be useful in case selection for ES. Whether it is clinically meaningful to monitor NF values for fetuses with isolated increased NT and normal chromosomes worth considering.

A Pain in the Neck: Lessons Learnt from Genetic Testing in Fetuses Detected with Nuchal Fluid Collections, Increased Nuchal Translucency versus Cystic Hygroma-Systematic Review of the Literature, Meta-Analysis and Case Series

Fetal Nuchal fluid collections can manifest with two distinct presentations attributable to the same phenotypic spectrum: increased nuchal translucency (iNT) and cystic hygroma. The prenatal detection of these findings should prompt an accurate assessment through genetic counseling and testing, including karyotype, chromosomal microarray analysis (CMA) and multigene RASopathy panel. We performed a systematic review of the literature and meta-analysis, to calculate diagnostic yields of genetic testing in fetuses with iNT and cystic hygroma. We compared the results with a cohort of 96 fetuses with these isolated findings. Fetuses with isolated NT ≥ 2.5 mm showed karyotype anomalies in 22.76% of cases and CMA presented an incremental detection rate of 2.35%. Fetuses with isolated NT ≥ 3 mm presented aneuploidies in 14.36% of cases and CMA had an incremental detection rate of 3.89%. When the isolated NT measured at least 3.5 mm the diagnostic yield of karyotyping was 34.35%, the incremental CMA detection rate was 4.1%, the incremental diagnostic rate of the RASopathy panel was 1.44% and it was 2.44% for exome sequencing. Interestingly, CMA presents a considerable diagnostic yield in the group of fetuses with NT ≥ 3.5 mm. Similarly, exome sequencing appears to show promising results and could be considered after a negative CMA result.

Clinical Application of Chromosomal Microarray Analysis in Pregnant Women with Advanced Maternal Age and Fetuses with Ultrasonographic Soft Markers

Background

In pregnant women with advanced maternal age (AMA) and fetuses with ultrasonographic (USG) soft markers it is always challenging to decide whether to implement chromosomal microarray analysis (CMA) or not. It is unclear whether CMA should be used in the fetuses with isolated USG soft markers, and there is still a lack of extensive sample research.

Material/Methods

We enrolled 1521 cases in our research and divided them into 3 groups as follows: pregnant women with isolated AMA (group 1, n=633), pregnant women whose fetuses had isolated USG soft markers (group 2, n=750), and pregnant women with AMA whose fetuses had isolated USG soft markers (group 3, n=138). All pregnant women underwent prenatal ultrasound and amniocentesis, and fetal cells in the amniotic fluid were used for genetic analysis of CMA. All participants signed a written informed consent prior to CMA.

Results

Abnormal findings were detected by CMA in 330 (21.70%) fetuses, including 37 (2.43%) clinically significant copy number variations (CNVs), 52 (3.42%) benign or likely benign CNVs, and 240 (15.78%) variants of unknown significance. The frequency of clinically significant CNVs in group 1 and group 2 were significantly lower than that in group 3 (2.37% and 2.0% vs 5.07%, P<0.01). More than a half (59.46%, 22/37) of the pregnant women decided to continue their pregnancy despite having a fetus diagnosed with clinically significant CNV.

Conclusions

CMA can increase the diagnostic yield of fetal chromosomal abnormality for pregnant women with isolated AMA or/and their fetuses had isolated USG soft markers.

Pregnant Hispanic women's views and knowledge of prenatal genetic testing

Pregnant Hispanic women are underserved with their needs for genetic counseling, despite birth defects remaining the leading cause of infant death in the United States. We present the qualitative findings of a study to understand knowledge and perceptions of prenatal testing in a sample of hard‐to‐reach underrepresented Hispanic pregnant women in South Texas. The sample for this study was 10 Hispanic pregnant women who were recruited from a high‐risk prenatal clinic in South Texas in 2019. The semi‐structured interview questions were created based on the researchers' clinical experiences with this population and were designed to examine knowledge and perceptions of participants toward prenatal testing. Analysis of the qualitative data yielded several themes related to prenatal testing: (a) knowledge, (b) confusion, (c) partner's and support persons' opinions, (d) information sharing from providers, (e) psychological benefits, (f) preparation for baby, (g) obstacles, (h) religious influence, and (i) educational tools to assist with understanding. Women's understanding and knowledge of prenatal testing was limited, specifically regarding its purpose, how it works, the benefits, and why it was recommended by their provider. Lack of clarity about why they should take the test and its risks for them and their babies was perceived as something that could impede their acceptance of prenatal testing. All participants agreed that healthcare providers should share more information about prenatal testing in a way that uses ‘everyday language' so that they can understand it better. All respondents mentioned that prenatal testing provides information about their baby's health conditions, alleviates their stress and concerns, and psychologically prepares them and their family for what is to come. Identifying ways to increase culturally appropriate education delivered by genetic counselors such as through the adoption of telemedicine and mobile technology can help fill the gap for this underserved population.

Outcome of fetuses with soft markers: results of 3016 cases in Ahvaz city

Background: Although soft markers may be seen as normal variants, they are important due to their association with chromosomal and congenital abnormalities. Methods: This cross-sectional descriptive-analytical study was done on 3016 women who referred for perinatal care. Fetuses with any of soft markers including thickened nuchal fold (TNF), mild pyelectasis (MP), choroid plexus cyst (CPC), single umbilical artery (SUA), mega cisterna magna (MCM) and mild ventriculomegaly (MVM) were followed during pregnancy and birth. Data analysis was carried out using SPSS for Windows (version 22). Data were analyzed using chi-square and T-test. A p-value <0.050 was considered statistically significant. Results: 285 (9.4%) fetuses with soft markers Including 148 (4.9%) fetuses with CPC, 118 (3.9%) fetuses with MP, 2 (0.1%,) fetuses with isolated TNF, 8 (0.3%) fetuses with isolated MVM, 4 (0.13%) fetuses with SUA, 4 (0.13%) fetuses with MCM were identified, and one fetus had TNF and MVM simultaneously. In cases with CPC, no abortion or major structural abnormalities were observed and all 148 neonates had normal phenotypes at birth. Among 118 cases with MP, one case had a major cardiac disorder, and 2 cases of abortions (1.7%) were reported (p=0.481). 83 cases (70.3%) were male and 35 cases (29.7%) were female (p=0.021) and all neonates had a normal phenotype. Both pregnancies with isolated TNF resulted in abortion. Of the 8 cases with isolated MVM, two cases had major structural abnormalities. 2 cases of abortion were reported and all infants had a normal phenotype. In one case, that fetus had TNF and MVM simultaneously. Amniocentesis showed no aneuploidy. No major structural abnormalities were observed in fetuses with SUA. One case of abortion was reported. Among the three births, two pre-term births were reported, and all three infants had normal phenotype. In four cases with MCM, no major structural abnormality was observed and all four neonates had normal phenotype. Conclusion: In cases without association with other structural abnormality, mothers who have fetuses with CPC or MP should be reassured that the pregnancy outcomes are generally favorable.

Should chromosomal microarray be offered to fetuses with ultrasonographic soft markers in second trimester: A prospective cohort study and meta-analysis

OBJECTIVE

To evaluate whether chromosomal microarray (CMA) should be offered to fetuses with ultrasonographic soft markers (USMs) in the second trimester.

METHODS

A prospective cohort study and meta-analysis were conducted. In the prospective cohort study, 564 fetuses with USMs were enrolled. In the meta-analysis, eligible articles describing copy number variations in fetuses with USMs were included.

RESULTS

In the prospective cohort study, the diagnostic yields of CMA over non-invasive prenatal testing (NIPT) and karyotyping were significantly higher in fetuses with mild ventriculomegaly (MVM) than those in local control cohorts with normal ultrasound. However, the yields of CMA over NIPT and karyotyping in fetuses with other USMs were similar to controls. About ten studies, involving 405 fetuses with MVM and 1412 fetuses with other USMs, were included in the meta-analysis. The pooled diagnostic yields of CMA over NIPT and karyotyping in fetuses with MVM were 4.9% and 3.2%, respectively. In fetuses with other USMs, the yields of CMA over NIPT and karyotyping were 1.2% and 0.4%, respectively.

CONCLUSION

It is reasonable to offer CMA as a first-tier test to fetuses with MVM. However, for fetuses with other USMs, the considerations to perform CMA should not differ from pregnancies with normal ultrasound.