Women's attitudes towards disclosure of genetic information in pregnancy with varying levels of penetrance

BACKGROUND

Chromosomal-microarray-analysis (CMA) may reveal susceptibility-loci (SL) of varied penetrance for autism-spectrum-disorder (ASD) and other neurodevelopmental conditions. Attitudes of women/parents to disclosure of SL during pregnancy are understudied.

METHODS

A multiple-choice questionnaire was distributed to postpartum women. Data were collected on women's interest to receive prenatal genetic information with various levels of penetrance.

RESULTS

Women's (n = 941) disclosure choices were dependent on the magnitude of risk: approximately 70% supported disclosure of either full or 40% penetrance, 53% supported disclosure at a 20% risk threshold, and 40% supported disclosure at 10% or less. Although most women supported, rejected or were indecisive about disclosure consistently across all risk levels, nearly one-quarter (24%) varied their responses based on penetrance, and this was associated with religiosity, education, parity and concern about fetal health (p-values <0.04). Among those who varied their choices, the risk threshold was lower among secular women (20%) than among ultraorthodox women (40%). In a multivariable analysis, ultraorthodox women were much less likely to vary their choices on ASD disclosure compared with secular women (aOR = 0.37, p < 0.001).

CONCLUSION

Women's attitudes toward disclosure are influenced by the level of risk and their individual characteristics. We therefore encourage engaging women/couples in disclosure decisions regarding uncertain and probabilistic results from prenatal genomic tests.

A Case Report of Familial Mayer-Rokitansky-Küster-Hauser Syndrome as Part of the Phenotypic Spectrum of the 2q37 Deletion

We performed a genetic investigation into the case of an inherited Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome. Our patients were an adolescent and her mother, both with MRKH syndrome. The delivery of a biological offspring was achieved via a gestational carrier. Karyotype and exome sequencing were used to complete a three-generation genetic analysis of the family. Both the mother and her daughter harbored a deletion of 4 Mb at the locus of 2q37, a syndrome rarely described in association with MRKH. No pathogenic single-nucleotide variant relevant to the phenotype was found. The deletion was not inherited from either parent of the mother. In addition, some physical findings suggesting 2q37 deletion syndrome were found in our patients. We conclude that when combined with the use of a gestational carrier or uterine transplantation, the identification of a genetic cause for MRKH may enable the application of preimplantation genetic testing on embryos, thus potentially averting the transmission of the genetic anomaly to subsequent generations.

Homozygous 22q11.2 distal type II microdeletion is associated with syndromic neurodevelopmental delay

Genomic disorders result from heterozygous copy number variants (CNVs). Homozygous deletions spanning numerous genes are rare, despite the potential contribution of consanguinity to such instances. CNVs in the 22q11.2 region are mediated by nonallelic homologous recombination between pairs of low copy repeats (LCRs), from amongst eight LCRs designated A-H. Heterozygous distal type II deletions (LCR-E to LCR-F) have incomplete penetrance and variable expressivity, and can lead to neurodevelopmental issues, minor craniofacial anomalies, and congenital abnormalities. We report siblings with global developmental delay, hypotonia, minor craniofacial anomalies, ocular abnormalities, and minor skeletal issues, in whom chromosomal microarray identified a homozygous distal type II deletion. The deletion was brought to homozygosity as a result of a consanguineous marriage between two heterozygous carriers of the deletion. The phenotype of the children was strikingly more severe and complex than that of the parents. This report suggests that the distal type II deletion harbors a dosage-sensitive gene or regulatory element, which leads to a more severe phenotype when deleted on both chromosomes.

Detection of copy number variants associated with late-onset conditions in ~16 200 pregnancies: parameters for disclosure and pregnancy outcome

BACKGROUND

Copy number variants (CNVs) associated with late-onset medical conditions are rare but important secondary findings in chromosomal microarray analysis (CMA) performed during pregnancy. Here, we critically review the cases at two tertiary centres to assess the criteria which guide the disclosure of such findings and develop a disclosure decision tool (DDT) aimed at facilitating disclosure decision. Parental decisions on receiving CNVs associated with risks for late-onset conditions were also recorded.

METHODS

Prenatal CMAs in Hadassah and Shaare Zedek Medical Centers from November 2013 to October 2021 were reviewed for CNVs associated with late-onset conditions. The DDT proposed uses a five-parameter scoring system, which considers the severity, median age of onset, penetrance, understanding of genotype-phenotype correlation and actionability of the finding.

RESULTS

Out of 16 238 prenatal CMAs, 16 (0.1%) harboured CNVs associated with late-onset conditions, 15 of which were disclosed. Outcome information was available on 13 of the 16 pregnancies, all of which continued to delivery.

CONCLUSIONS

Our suggested DDT will help clinicians to quantitatively weigh the variables associated with CNVs of this type and arrive at a well thought out clinical decision regarding disclosure. Although the prevalence of late-onset conditions as a major finding in the prenatal setup is low, it is expected to rise with the increasing use of non-invasive CMA testing and whole exome and genome sequencing.

Postpartum women's attitudes to disclosure of adult-onset conditions in pregnancy

Background

Advanced prenatal genomic technologies can identify risks for adult‐onset (AO) conditions in the fetus, challenging the traditional purpose of prenatal testing. Professional guidelines commonly support disclosure of high‐penetrance AO actionable conditions, yet attitudes of women/parents to these findings and factors affecting their attitudes are understudied.

Methods

We explored 941 (77% response rate) postpartum women's attitudes towards receiving prenatal genetic information, and associations of sociodemographic, medical and psychological characteristics with their choices, focusing on AO conditions.

Results

Women largely support the disclosure of actionable AO findings (58.4%), in line with professional guidelines. A third of the women also supported the disclosure of non‐actionable AO conditions. Stronger religious observance (p < 0.001) and higher psychological distress (p = 0.024) were associated with decreased interest in receiving actionable AO conditions, whereas higher concern for fetal health yielded increased interest (p = 0.032). Attitudes towards disclosure were strongly associated with women's perceived benefit of such information for their own, partner's, and future child's health. Termination of pregnancy based on such information received very little support.

Conclusion

In‐light of the demonstrated understanding of nuanced genetic information and the observed diversity in attitudes, a culturally competent opt‐in/out policy could be considered. If full‐disclosure is practiced, support should be provided to those expressing higher levels of distress.

What is known

Advanced prenatal genomic technologies can identify risks for adult‐onset (AO) conditions.

Professional guidelines support disclosure of high‐penetrance AO actionable conditions in pregnancy, yet attitudes of women/parents towards receiving this information are understudied.

What this study adds

Investigating the attitudes of nearly 1000 postpartum women demonstrates that women largely support the disclosure of actionable AO findings in pregnancy.

Stronger religious observance and higher psychological distress predict decreased interest in receiving this information.

CRISPR/Cas9-induced gene conversion between ATAD3 paralogs

Paralogs and pseudogenes are abundant within the human genome, and can mediate non-allelic homologous recombination (NAHR) or gene conversion events. The ATAD3 locus contains three paralogs situated in tandem, and is therefore prone to NAHR-mediated deletions and duplications associated with severe neurological phenotypes. To study this locus further, we aimed to generate biallelic loss-of-function variants in ATAD3A by CRISPR/Cas9 genome editing. Unexpectedly, two of the generated clones underwent gene conversion, as evidenced by replacement of the targeted sequence of ATAD3A by a donor sequence from its paralog ATAD3B. We highlight the complexity of CRISPR/Cas9 design, end-product formation, and recombination repair mechanisms for CRISPR/Cas9 delivery as a nucleic acid molecular therapy when targeting genes that have paralogs or pseudogenes, and advocate meticulous evaluation of resultant clones in model organisms. In addition, we suggest that endogenous gene conversion may be used to repair missense variants in genes with paralogs or pseudogenes.

The many etiologies of nonimmune hydrops fetalis diagnosed by exome sequencing

OBJECTIVE

To explain the importance of identifying an etiology for the pathological finding of nonimmune hydrops fetalis (NIHF) and to explore the impact of exome sequencing in recurrent NIHF. In addition, we present two cases of pregnancies affected with recurrent NIHF, in which genetic investigation was advantageous.

METHODS

Our study aimed to investigate the genetic background, if available, of all fetuses with NIHF referred to our tertiary medical center from January 2013 to August 2020. We summarized the etiology of NIHF if known, sonographic findings, genetic investigation and the pregnancies' outcomes.

RESULTS

We encountered 144 families with NIHF. Genetic investigation was performed by chromosomal microarray analysis (CMA) in 63 (63/144. 44%) fetuses. Seventeen of 63 (27%) had a positive CMA result. In the negative CMA group, 15 (15/46, 33%) opted for exome sequencing, of which seven exomes were positive (47%). Among these, there were four couples with recurrent pregnancies affected by hydrops. Among the remaining 11 exome investigations for non-recurrent hydrops, another three were diagnostic.

CONCLUSION

As identifying the etiology of the NIHF is an invaluable tool for the prognosis of the pregnancy, exome sequencing can provide further elucidation of the underlying pathogenesis of NIHF. Thus, genetic investigation should be recommended for cases of NIHF.

Universal chromosomal microarray analysis reveals high proportion of copy-number variants in low-risk pregnancies

OBJECTIVES

To evaluate the yield and utility of the routine use of chromosomal microarray analysis (CMA) for prenatal genetic diagnosis in a large cohort of pregnancies with normal ultrasound (US) at the time of genetic testing, compared with pregnancies with abnormal US findings.

METHODS

We reviewed all prenatal CMA results in our center between November 2013 and December 2018. The prevalence of different CMA results in pregnancies with normal US at the time of genetic testing ('low-risk pregnancies'), was compared with that in pregnancies with abnormal US findings ('high-risk pregnancies'). Medical records were searched in order to evaluate subsequent US follow-up and the outcome of pregnancies with a clinically relevant copy-number variant (CNV), i.e. a pathogenic or likely pathogenic CNV or a susceptibility locus for disease with > 10% penetrance, related to early-onset disease in the low-risk group.

RESULTS

In a cohort of 6431 low-risk pregnancies that underwent CMA, the prevalence of a clinically significant CNV related to early-onset disease was 1.1% (72/6431), which was significantly lower than the prevalence in high-risk pregnancies (4.9% (65/1326)). Of the low-risk pregnancies, 0.4% (27/6431) had a pathogenic or likely pathogenic CNV, and another 0.7% (45/6431) had a susceptibility locus with more than 10% penetrance. Follow-up of the low-risk pregnancies with a clinically significant early-onset CNV revealed that 31.9% (23/72) were terminated, while outcome data were missing in 26.4% (19/72). In 16.7% (12/72) of low-risk pregnancies, an US abnormality was discovered later on in gestation, after genetic testing had been performed.

CONCLUSION

Although the background risk of identifying a clinically significant early-onset abnormal CMA result in pregnancies with a low a-priori risk is lower than that observed in high-risk pregnancies, the risk is substantial and should be conveyed to all pregnant women. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Whole-genome sequencing reveals complex chromosome rearrangement disrupting NIPBL in infant with Cornelia de Lange syndrome

Clinical laboratory diagnostic evaluation of the genomes of children with suspected genetic disorders, including chromosomal microarray and exome sequencing, cannot detect copy number neutral genomic rearrangements such as inversions, balanced translocations, and complex chromosomal rearrangements (CCRs). We describe an infant with a clinical diagnosis of Cornelia de Lange syndrome (CdLS) in whom chromosome analysis revealed a de novo complex balanced translocation, 46,XY,t(5;7;6)(q11.2;q32;q13)dn. Subsequent molecular characterization by whole-genome sequencing (WGS) identified 23 breakpoints, delineating segments derived from four chromosomes (5;6;7;21) in ancestral or inverted orientation. One of the breakpoints disrupted a known CdLS gene, NIPBL. Further investigation revealed paternal origin of the CCR allele, clustering of the breakpoint junctions, and molecular repair signatures suggestive of a single catastrophic event. Notably, very short DNA segments (25 and 41 bp) were included in the reassembled chromosomes, lending additional support that the DNA repair machinery can detect and repair such segments. Interestingly, there was an independent paternally derived miniscule complex rearrangement, possibly predisposing to subsequent genomic instability. In conclusion, we report a CCR causing a monogenic Mendelian disorder, urging WGS analysis of similar unsolved cases with suspected Mendelian disorders. Breakpoint analysis allowed for identification of the underlying molecular diagnosis and implicated chromoanagenesis in CCR formation.

Single-nucleotide polymorphism-based chromosomal microarray analysis provides clues and insights into disease mechanisms

OBJECTIVE

Chromosomal microarray analysis (CMA) is the modality of choice for prenatal diagnosis in pregnancy with fetal malformation, as it has a high diagnostic yield for microdeletion/duplication syndromes. The aim of this study was to demonstrate the additional utility of single-nucleotide polymorphism (SNP)-based CMA in diagnosing monogenic diseases, imprinting disorders and uniparental disomy (UPD).

METHODS

CMA was performed using Affymetrix CytoScan array, for all indications in 6995 pregnancies, at a tertiary referral hospital from November 2013 to June 2018. We describe four cases that had a CMA result that provided a more comprehensive understanding of the complex genetic mechanisms underlying the clinical presentation.

RESULTS

In the first fetus, CMA was performed due to intrauterine growth restriction and revealed a 75 kbp maternally inherited microdeletion encompassing the Bloom syndrome gene (BLM). A diagnosis of Bloom syndrome was made upon identifying a paternally inherited common Ashkenazi founder mutation. In the second case, CMA was performed due to severely abnormal maternal serum analytes and revealed a deletion in 14q32.2q32.31 on the maternally inherited copy, leading to a diagnosis of Kagami-Ogata syndrome, which is an imprinting disorder. In the third case, amniocentesis was performed because of late-onset fetal macrosomia and mild polyhydramnios. CMA detected a deletion encompassing the locus of Prader-Willi/Angelman syndrome. In the fourth case, amniocentesis was performed due to maternal cytomegalovirus seroconversion. Maternal UPD of the entire long arm of chromosome 11 was detected.

CONCLUSION

Prenatal CMA, based on oligo and SNP platforms, increases the diagnostic yield and enables a wider spectrum of disorders to be detected through the identification of complex genetic etiologies beyond only copy number variants. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Is fetal isolated double renal collecting system an indication for chromosomal microarray?

Introduction: Duplication of the renal collecting system is one of the most common variants of urinary tract anatomy. The objective of our study was to examine the risk for chromosomal aberrations in this isolated prenatal sonographic finding.Methods: Data from all chromosomal microarray analyses (CMA) reported to the Ministry of Health between January 2013 and September 2017 were retrospectively obtained from a computerized database. All pregnancies with a sonographic diagnosis of the isolated duplex renal collecting system and documentation of CMA result were included. Rate of abnormal CMA findings was compared to the general population risk, based on a systematic review encompassing 9272 cases with normal ultrasound and a local data of 5541 pregnancies undergoing CMA due to maternal request.Results: Two pathogenic CMA finding was found amongst 143 pregnancies with double collecting system (1.4%), not significantly different from the risk for abnormal CMA results in the general population. In addition, five variants of unknown significance were demonstrated (3.5%).Conclusion: To our best knowledge, this analysis is the first report describing the rate of chromosomal anomalies in pregnancies with isolated duplex renal collecting system. Its results suggest that routine invasive prenatal testing with CMA analysis in such cases is no more useful than in the general population. Prospective well-adjusted studies are needed to guide the optimal management of these pregnancies.

Role of late amniocentesis in the era of modern genomic technologies

OBJECTIVE

Traditionally, amniocentesis is performed between 17 and 23 weeks of gestation. This enables decisions regarding the course of pregnancy to be made before viability. Less frequently, amniocentesis is performed in the third trimester. Advanced genomic technologies such as chromosomal microarray analysis (CMA) provide more detailed information about the fetus compared with traditional G-banded chromosomal analysis. The aim of this study was to assess the indications for and safety of late amniocentesis, genetic-test results (especially in the context of CMA technology) and outcome of pregnancies that underwent the procedure after 24 weeks.

METHODS

Medical records were analyzed retrospectively of all women in whom amniocentesis was performed at a gestational age of 24 + 0 to 38 + 6 weeks, at Hadassah Medical Center, between June 2013 and March 2017. Parameters investigated included indications for late amniocentesis, complications, CMA results and pregnancy outcome.

RESULTS

During the study period, 291 women (303 fetuses, 277 singleton and 14 twin pregnancies; in two twin pairs, one fetus was terminated before amniocentesis) underwent late amniocentesis. CMA was performed in all instances of amniocentesis. The most frequent indication was abnormal sonographic finding(s) (204/303 fetuses, 67%). Preterm delivery occurred in 1.7% and 5.1% of pregnancies within the first week and within 1 month following the procedure, respectively. Aneuploidy was detected in nine (3%) fetuses and nine (3%) others had a pathogenic/likely pathogenic copy number variant, suggesting that CMA doubled the diagnostic yield of traditional karyotyping. Maximal diagnostic yield (17.5%) was achieved for the subgroup of fetuses referred with abnormal sonographic findings in two or more fetal anatomical systems. Variants of uncertain significance or susceptibility loci were found in another nine (3%) fetuses.

CONCLUSIONS

In pregnancies undergoing late amniocentesis, CMA increased detection rates of fetal abnormalities and had a shorter turnaround time compared with traditional chromosomal analysis; therefore, late amniocentesis may serve as a helpful tool for detecting fetal abnormalities or reassuring parents following late-appearing abnormal sonographic findings. However, CMA may expose findings of uncertain significance, about which the couple should be precounseled. The procedure appears to be safe. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Chromosomal microarray findings in pregnancies with an isolated pelvic kidney

Objective To examine the risk for abnormal chromosomal microarray analysis (CMA) results among fetuses with an apparently isolated pelvic kidney. Methods Data from all CMA analyses performed due to an isolated pelvic kidney reported to the Israeli Ministry of Health between January 2013 and September 2016 were retrospectively obtained. Risk estimation was performed comparing the rate of abnormal observed CMA findings to the general population risk, based on a systematic review encompassing 9272 cases and on local data of 5541 cases. Results Of 120 pregnancies with an isolated pelvic kidney, two gain-of-copy number variants suggesting microduplication syndromes were demonstrated (1.67%). In addition, three variants of unknown significance were detected (2.5%). Conclusion The risk for clinically significant CMA findings among pregnancies with an isolated single pelvic kidney was not significantly different compared to both control populations. The results of our study question the practice of routine CMA analysis in fetuses with an isolated pelvic kidney.

Isolated fetal horseshoe kidney does not seem to increase the risk for abnormal chromosomal microarray results

OBJECTIVE

To examine the risk for clinically significant chromosomal microarray analysis (CMA) among fetuses with apparently isolated horseshoe kidney.

METHODS

Data from all CMA analyses performed due to isolated horseshoe kidney reported to the Israeli Ministry of Health between January 2013 and September 2016 were retrospectively obtained from a computerized database. Risk estimation was performed comparing the rate of abnormal CMA findings to the general population, based on a systematic review encompassing 9272 pregnancies with normal ultrasound, and local data cohort of 5541 pregnancies undergoing CMA due to maternal request.

RESULTS

Of 82 pregnancies with isolated horseshoe kidney, one loss-of-copy-number variant compatible with 16p13.11 microdeletion syndrome was demonstrated (1.2%). In addition, two variants of unknown significance (VOUS) were detected (2.4%). The relative risk for pathogenic CMA findings among pregnancies with isolated single horseshoe kidney was not significantly different from the control population (1.03-1.39%).

DISCUSSION

To our best knowledge, our study is the first report describing the rate of clinically significant CMA findings in fetuses with isolated horseshoe kidney. The detection of one pathogenic CMA findings in our cohort implies that the value of CMA analysis in such pregnancies is similar to the general population.

Ultrasound findings provide clues to investigate founder mutations expressed as runs of homozygosity in chromosomal microarray studies

OBJECTIVES

Chromosomal microarray analysis is effectively applied prenatally to detect copy number changes. Single nucleotide polymorphism (SNP) probes included in the microarray platform can detect regions of excessive homozygosity and identical-by-descent genomic stretches. The utility of the latter as part of prenatal diagnosis is not well established. Recessive founder mutations are well recognized within distinct ethnic groups. Combining these data with prenatal sonography provides accurate focused molecular diagnoses quickly. We aimed to evaluate the application of this approach in expectant families presenting to our unit.

METHODS

Three unrelated gravidae presenting with specific fetal sonographic findings: (1) ventriculomegaly with encephalocele; (2) severe polyhydramnion; and (3) enlarged echogenic kidneys, underwent amniocentesis for chromosomal microarray analysis, and genome-wide human SNP array was used to analyze DNA from amniocytes. The Genomic Oligoarray and SNP array evaluation tool v3.0© was used to detect recessive loci associated with the reported clinical findings. Candidate genes were further interrogated using the Israeli National Genetic Database (INGD) and specifically searching and identifying a corresponding founder mutation within the defined ethnic group.

RESULTS

Three fetuses from 3 distinct nuclear families in which the parents shared a similar ethnicity (either Ashkenazi or Bukharan Jews) albeit no reported consanguinity were assessed. We found no copy number changes; however, by evaluating regions of homozygosity, we were able to reveal relevant candidate gene for the specific phenotype for each fetus. Using the INGD led to targeted testing of a specific homozygous fetal mutation for which parents were found to be carriers. In the fetus with ventriculomegaly with encephalocele c.1167dupA mutation in the FKTN gene, in the fetus with severe polyhydramnion c.167ins6[TTTCCC] mutation in the BSND gene, and in the fetus with enlarged echogenic kidneys, c.3761_3762delCCinsG in the PKHD1 gene were identified.

CONCLUSIONS

A tripartite approach integrating sonographic pathology with regions of excessive homozygosity data and INGD-based founder mutation repository yields a comprehensive streamlined approach to provide accurate genetic diagnosis and counselling within the time constraints of an ongoing pregnancy.