Confined placental mosaicism: Distribution of chromosomally abnormal cells over the term placenta.

OBJECTIVE: Non-invasive prenatal testing (NIPT) investigates placental DNA and may detect confined placental mosaicism (CPM). The aim of this study was to confirm CPM in the term placenta in cases with abnormal NIPT but normal follow-up cytogenetic studies of fetus and mother. Additionally we examined the distribution of abnormal cells over the placenta. METHODS: Four chorionic villus (CV) biopsies from four placental quadrants were requested in cases where CPM was assumed. Both cell lineages of the CV, cytotrophoblast (CTB) and mesenchymal core (MC), were analyzed separately with SNP array. RESULTS: The chromosome aberration was confirmed in 67 % of the placentas. Three quarters of the CTB and MC biopsies from these mosaic placentas were uniformly normal (57 %) or abnormal (20 %), and a minority showed mosaicism. Among 16 cases of CPM where first trimester CV were examined as well, 11 had chromosomally normal results during pregnancy. DISCUSSION: Cytogenetic investigations of term placental biopsies suspected to be affected with CPM did not reveal the chromosome aberration in one third of the placentas. This is caused by the patchy pattern in which chromosomally abnormal cells are distributed over the placenta with the majority of the biopsies being uniformly normal. Further CPM research, including its clinical impact, requires the analysis of more than four biopsies to get insight into the extent of the affected part. Moreover, a subset of CPM type 1 and 3 seems to be only detectable with NIPT and not with first trimester CVS.

The incremental yield of prenatal exome sequencing over chromosome microarray for congenital heart abnormalities: A systematic review and meta-analysis.

OBJECTIVES: To determine the incremental yield of prenatal exome sequencing (PES) over standard testing in fetuses with an isolated congenital heart abnormality (CHA), CHA associated with extra-cardiac malformations (ECMs) and CHA dependent upon anatomical subclassification. METHODS: A systematic review of the literature was performed using MEDLINE, EMBASE, Web of Science and grey literature January 2010-February 2023. Studies were selected if they included greater than 20 cases of prenatally diagnosed CHA when standard testing (QF-PCR/chromosome microarray/karyotype) was negative. Pooled incremental yield was determined. PROSPERO CRD 42022364747. RESULTS: Overall, 21 studies, incorporating 1957 cases were included. The incremental yield of PES (causative pathogenic and likely pathogenic variants) over standard testing was 17.4% (95% CI, 13.5%-21.6%), 9.3% (95% CI, 6.6%-12.3%) and 35.9% (95% CI, 21.0%-52.3%) for all CHAs, isolated CHAs and CHAs associated with ECMs. The subgroup with the greatest yield was complex lesions/heterotaxy; 35.2% (95% CI 9.7%-65.3%). The most common syndrome was Kabuki syndrome (31/256, 12.1%) and most pathogenic variants occurred de novo and in autosomal dominant (monoallelic) disease causing genes (114/224, 50.9%). CONCLUSION: The likelihood of a monogenic aetiology in fetuses with multi-system CHAs is high. Clinicians must consider the clinical utility of offering PES in selected isolated cardiac lesions.

Choosing between Higher and Lower Resolution Microarrays: do Pregnant Women Have Sufficient Knowledge to Make Informed Choices Consistent with their Attitude?

Developments in prenatal testing allow the detection of more findings. SNP arrays in prenatal diagnosis (PND) can be analyzed at 0.5 Mb resolution detecting more clinically relevant anomalies, or at 5 Mb resolution. We investigated whether women had sufficient knowledge to make informed choices regarding the scope of their prenatal test that were consistent with their attitude. Pregnant women could choose between testing at 5 or at 0.5 Mb array. Consenting women (N = 69) received pre-test genetic counseling by phone and filled out the Measure of Informed Choice questionnaire designed for this study. Choices based on sufficient knowledge and consistent with attitude were considered informed. Sixty-two percent of the women made an adequately informed choice, based on sufficient knowledge and attitude-consistent with their choice of microarray resolution. Women who made an informed choice, opted for 0.5 Mb array resolution more often. There were no differences between women making adequately informed or less informed choices regarding level of experienced anxiety or doubts. Over time on T0 and T1, anxiety and doubts significantly decreased. While previous studies demonstrated that knowledge is an important component in informed decision-making, this study underlines that a consistent attitude might be equally important for decision-making. We advocate more focus on attitude-consistency and deliberation as compared to only a strong focus on knowledge.

The Psychological Impact of Prenatal Diagnosis and Disclosure of Susceptibility Loci: First Impressions of Parents' Experiences.

Genomic microarray may detect susceptibility loci (SL) for neurodevelopmental disorders such as autism and epilepsy, with a yet unquantifiable risk for the fetus. The prenatal disclosure of susceptibility loci is a topic of much debate. Many health care professionals fear that reporting susceptibility loci may put a psychological burden on pregnant couples. It is our policy to disclose prenatal susceptibility loci as we recognize them as actionable for prospective parents. The aim of this report was to evaluate the psychological impact of disclosing a prenatal diagnosis of susceptibility loci. The psychological impact of disclosing susceptibility loci was evaluated in the first patients who received such results. Eight out of 15 women who had a susceptibility locus disclosed and four of their partners consented to share their experiences through a telephonic evaluation (n = 12). Follow-up time ranged from 3 to 15 months after their prenatal test result. The reporting of susceptibility loci was initially 'shocking' for five parents while the other seven felt 'worried'. Ten out of 12 participants indicated they would like to be informed about the susceptibility locus again, two were unsure. Most had no enduring worries. Participants unanimously indicated that pregnant couples should have an individualized pre-test choice about susceptibility loci (non)disclosure. We observed no negative psychological impact with the prenatal diagnosis and disclosure of SL on participants. A key factor in mitigating parental anxiety with SL disclosure appears to be post-test genetic counseling. Our report confirms that pregnant women and their partners prefer an individualized choice regarding the scope of prenatal testing.

Pregnant couples at increased risk for common aneuploidies choose maximal information from invasive genetic testing.

Genomic array detects more pathogenic chromosome aberrations than conventional karyotyping (CK), including genetic variants associated with a susceptibility for neurodevelopmental disorders; susceptibility loci (SL). Consensus regarding the scope of invasive prenatal diagnosis (PND) pregnant couples should be offered is lacking. This study examined pregnant couples' preferences, doubts and satisfaction regarding the scope of invasive PND. Eighty-two couples choosing prenatal screening (PNS) and 59 couples choosing invasive PND were offered a choice between 5 (comparable to CK) and 0.5 Mb resolution array analysis outcomes, the latter with or without reporting SL. A pre-test self-report questionnaire and post-test telephone interview assessed their choices in-depth. Actual (PND) and hypothetical (PNS) choices differed significantly (p < 0.001). Ninety-five percent of the couples in the PND group chose 0.5 Mb array, vs 69% in the PNS group. Seven percent of the PND group wished not to be informed of SL. Ninety percent was satisfied with their choice and wished to decide about the scope themselves. Pregnant couples wish to make their own choices regarding the scope of invasive PND. It therefore seems justified to offer them a choice in both the resolution of array and disclosure of SL.

Abnormal non-invasive prenatal test results concordant with karyotype of cytotrophoblast but not reflecting abnormal fetal karyotype.

We present a unique case in which non-invasive and invasive prenatal diagnoses showed abnormal, but discordant, results. A patient with abnormal non-invasive prenatal test (NIPT) results, indicating a 99% risk for monosomy X, was referred to our center for genetic counseling and confirmatory studies. Cytogenetic analysis of uncultured mesenchymal core of chorionic villi (CV) revealed a mosaic male karyotype consisting of two abnormal cell lines: one with monosomy X and the other with an isodicentric chromosome Y. Array analysis of the trophoblast confirmed the NIPT results. Based on the CV results, the patient opted for termination of pregnancy. After extensive counseling by a clinical geneticist about the possible outcomes and by a gynecologist about the risk of a second-trimester abortion procedure, the patient agreed to undergo early amniocentesis. Amniocentesis confirmed that the fetus had a male karyotype with an isodicentric chromosome Y, and the single nucleotide polymorphism (SNP) array profile suggested absence of the monosomy X cell line. The male infant was expected to be infertile. The patient finally decided to continue the pregnancy. Our case confirms that NIPT results are comparable with those of short-term cultured CV investigating the cytotrophoblast. Our patient was not aware that the NIPT results reveal the placental karyotype, which sometimes may be different from the fetal karyotype. Pretest counseling and providing the risk figures for false-positive and false-negative NIPT results are of great importance in order to discourage women from terminating pregnancies based on NIPT results alone.