Prenatal Array Comparative Genomic Hybridization in Fetuses With Structural Cardiac Anomalies

Chromosomal Microarray Analysis in Fetuses Detected with Isolated Cardiovascular Malformation: A Multicenter Study, Systematic Review of the Literature and Meta-Analysis

Cardiovascular malformations (CVM) represent the most common structural anomalies, occurring in 0.7% of live births. The CVM prenatal suspicion should prompt an accurate investigation with fetal echocardiography and the assessment through genetic counseling and testing. In particular, chromosomal microarray analysis (CMA) allows the identification of copy number variations. We performed a systematic review and meta-analysis of the literature, studying the incremental diagnostic yield of CMA in fetal isolated CVM, scoring yields for each category of heart disease, with the aim of guiding genetic counseling and prenatal management. At the same time, we report 59 fetuses with isolated CVM with normal karyotype who underwent CMA. The incremental CMA diagnostic yield in fetuses with isolated CVM was 5.79% (CI 5.54–6.04), with conotruncal malformations showing the higher detection rate (15.93%). The yields for ventricular septal defects and aberrant right subclavian artery were the lowest (2.64% and 0.66%). Other CVM ranged from 4.42% to 6.67%. In the retrospective cohort, the diagnostic yield was consistent with literature data, with an overall CMA diagnostic yield of 3.38%. CMA in the prenatal setting was confirmed as a valuable tool for investigating the causes of fetal cardiovascular malformations.

Molecular Approaches in Fetal Malformations, Dynamic Anomalies and Soft Markers: Diagnostic Rates and Challenges-Systematic Review of the Literature and Meta-Analysis

Fetal malformations occur in 2-3% of pregnancies. They require invasive procedures for cytogenetics and molecular testing. "Structural anomalies" include non-transient anatomic alterations. "Soft markers" are often transient minor ultrasound findings. Anomalies not fitting these definitions are categorized as "dynamic". This meta-analysis aims to evaluate the diagnostic yield and the rates of variants of uncertain significance (VUSs) in fetuses undergoing molecular testing (chromosomal microarray (CMA), exome sequencing (ES), genome sequencing (WGS)) due to ultrasound findings. The CMA diagnostic yield was 2.15% in single soft markers (vs. 0.79% baseline risk), 3.44% in multiple soft markers, 3.66% in single structural anomalies and 8.57% in multiple structural anomalies. Rates for specific subcategories vary significantly. ES showed a diagnostic rate of 19.47%, reaching 27.47% in multiple structural anomalies. WGS data did not allow meta-analysis. In fetal structural anomalies, CMA is a first-tier test, but should be integrated with karyotype and parental segregations. In this class of fetuses, ES presents a very high incremental yield, with a significant VUSs burden, so we encourage its use in selected cases. Soft markers present heterogeneous CMA results from each other, some of them with risks comparable to structural anomalies, and would benefit from molecular analysis. The diagnostic rate of multiple soft markers poses a solid indication to CMA.

Prenatal diagnosis of a de novo 15q11.2 microdeletion in a maternal inv(4)(p15q31) fetus with increased nuchal translucency: A case report and literature review

RATIONALE

15q11.2 microdeletion syndrome is a relatively rare chromosomal abnormality with incomplete penetrance and phenotypic variability. The reports on prenatal ultrasound abnormalities of fetus with 15q11.2 microdeletion are rare.

PATIENT CONCERNS

A 30-year-old woman was referred for genetic counseling and prenatal diagnosis at 19 weeks of gestation because of increased nuchal translucency in prenatal ultrasound findings and a history of spontaneous abortion.

DIAGNOSES

The cytogenetic analysis showed the karyotype of the fetus was 46,XY, inv(4)(p15q31) and chromosomal microarray analysis detected a 0.512 Mb deletion in 15q11.2 region. We recalled the parents to determine the origination of these chromosomal abnormalities.

INTERVENTIONS

The pregnant woman chose to continue the pregnancies and finally delivered a healthy male infant at 39 weeks.

OUTCOMES

The fetus inherited the inv(4)(p15q31) from his mother while the deletion in 15q11.2 was identified as de novo. Given the normal phenotype of the mother, it was reasonable to assume that the maternal inherited inv(4) in the fetus would not increase the risk of his abnormal phenotype. However, the pathogenicity of the microdeletion in 15q11.2 for the infant is unknown and long-term follow-up of progeny should be paid more attention.

LESSONS

The combined application of traditional banding technique and molecular cytogenetic techniques can not only detect chromosomal structural abnormalities, but also identify the subchromosomal imbalances, which is beneficial to genetic counselling and would offer more guidance to prenatal diagnosis.

Genetic Basis of Human Congenital Heart Disease

Congenital heart disease (CHD) is the most common major congenital anomaly with an incidence of ∼1% of live births and is a significant cause of birth defect-related mortality. The genetic mechanisms underlying the development of CHD are complex and remain incompletely understood. Known genetic causes include all classes of genetic variation including chromosomal aneuploidies, copy number variants, and rare and common single-nucleotide variants, which can be either de novo or inherited. Among patients with CHD, ∼8%-12% have a chromosomal abnormality or aneuploidy, between 3% and 25% have a copy number variation, and 3%-5% have a single-gene defect in an established CHD gene with higher likelihood of identifying a genetic cause in patients with nonisolated CHD. These genetic variants disrupt or alter genes that play an important role in normal cardiac development and in some cases have pleiotropic effects on other organs. This work reviews some of the most common genetic causes of CHD as well as what is currently known about the underlying mechanisms.

Prenatally diagnosed de novo segmental amplification or deletion by microarray-based comparative genomic hybridization: A retrospective study

OBJECTIVE

Prenatal diagnosis of de novo segmental amplification or deletion by microarray-based comparative genomic hybridization (array CGH) is uncommon. The study aimed to know about the incidence, abnormal ultrasound findings, and pregnancy outcomes of prenatally diagnosed de novo segmental amplification or deletion by array CGH.

MATERIALS AND METHODS

Between January 2014 and December 2017, we analyzed pregnant women who received prenatal array CGH (SurePrint G3 Human CGH Microarray Kit, 8 × 60K) at Chang Gung Memorial Hospital, Taiwan. Clinical data on maternal age, reason for fetal karyotyping, sonographic findings, gestational age at delivery, newborn birth weight, and associated anomalies, if any, were obtained by chart review.

RESULTS

A total of 836 specimens (814 amniotic fluid samples, 4 cord blood samples, 18 chorionic villi samples) were analyzed by array CGH during the study period. Of the 56 cases with abnormal array CGH results, 40 had segmental amplification or deletion, 12 had trisomy, three had monosomy, and one had sex chromosome aneuploidy. Of these 40 cases with segmental amplification or deletion, 30 were inherited and 10 were de novo occurrences. The incidence of de novo segmental amplification or deletion was 1.2% (10/836). Abnormal prenatal ultrasound findings occurred in 40% (4/10) of de novo segmental amplification or deletion cases. Among these 10 pregnancies, nine were voluntarily terminated between 22 and 26 weeks of gestation and one was delivered at term.

CONCLUSIONS

Prenatal diagnosis of de novo segmental amplification or deletion by array CGH raises important genetic counseling issues. In our series, the incidence of de novo segmental amplification or deletion in prenatal samples was 1.2%. Abnormal prenatal sonographic findings occurred in 40% of these de novo segmental amplification or deletion cases. Of these de novo segmental amplification or deletion pregnancies, 90% were voluntarily terminated.

The genetics of isolated congenital heart disease

The genetic mechanisms underlying congenital heart disease (CHD) are complex and remain incompletely understood. The majority of patients with CHD have an isolated heart defect without other organ system involvement, but the genetic basis of isolated CHD has been even more difficult to elucidate compared to syndromic CHD. Our understanding of the genetics of isolated CHD is advancing in large part due to advances in next generation sequencing, and the list of genes associated with CHD is rapidly expanding. Variants in hundreds of genes have been identified that may cause or contribute to CHD, but a genetic cause can still only be identified in about 20-30% of patients. Identifying a genetic cause for CHD can have an impact on clinical outcomes and prognosis and thus it is important for clinicians to understand when and what to test in patients with isolated CHD. This chapter reviews some of the known genetic mechanisms that contribute to isolated inherited and sporadic CHD as well as recommendations for evaluation and genetic testing in patients with isolated CHD.

Next-Generation Sequencing Using a Cardiac Gene Panel in Prenatally Diagnosed Cardiac Anomalies

OBJECTIVE

Most prenatally identified congenital heart defects (CHDs) are the sole structural anomaly detected; however, there is a subgroup of cases where the specific genetic cause will impact prognosis, including chromosome abnormalities and single-gene causes. Next-generation sequencing of all the protein coding regions in the genome or targeted to genes involved in cardiac development is currently possible in the prenatal period, but there are minimal data on the clinical utility of such an approach. This study assessed the outcome of a CHD gene panel that included single-gene causes of syndromic and non-syndromic CHDs.

METHOD

Sixteen cases with a fetal CHD identified on prenatal ultrasound were studied using a 108 CHD gene panel. DNA was extracted from cultured amniocytes.

RESULTS

There was no diagnostic pathogenic variant identified in these cases. There was an average of 2.9 reportable variants identified per case and the majority of them were variants of uncertain significance.

CONCLUSION

Next-generation sequencing has the potential for increased genetic diagnosis for fetal anomalies. However, the large number of variants and the absence of an examinable patient make the interpretation of these variants challenging.

Fetal cardiac abnormalities: Genetic etiologies to be considered

Congenital heart diseases are a common prenatal finding. The prenatal identification of an associated genetic syndrome or a major extracardiac anomaly helps to understand the etiopathogenic diagnosis. Besides, it also assesses the prognosis, management, and familial recurrence risk while strongly influences parental decision to choose termination of pregnancy or postnatal care. This review article describes the most common genetic diagnoses associated with a prenatal finding of a congenital heart disease and a suggested diagnostic process.

Prenatal diagnosis of a familial 15q11.2 (BP1-BP2) microdeletion encompassing TUBGCP5, CYFIP1, NIPA2 and NIPA1 in a fetus with ventriculomegaly, microcephaly and intrauterine growth restriction on prenatal ultrasound

OBJECTIVE

We present prenatal diagnosis of a 15q11.2 (BP1-BP2) microdeletion encompassing TUBGCP5, CYFIP1, NIPA2 and NIPA1 in a fetus with ventriculomegaly, microcephaly and intrauterine growth restriction (IUGR) on prenatal ultrasound.

CASE REPORT

A 30-year-old, gravida 3, para 2, woman was referred to the hospital for amniocentesis because of fetal ventriculomegaly on prenatal ultrasound. Her husband was 31 years old. The couple had two healthy daughters, and there was no family history of mental disorders and congenital malformations. Amniocentesis revealed a karyotype of 46,XX. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed a 451.89-kb 15q11.2 microdeletion or arr 15q11.2 (22,765,628-23,217,514) × 1.0 [GRCh37 (hg19)] encompassing TUBGCP5, CYFIP1, NIPA2 and NIPA1. The parental karyotypes were normal. aCGH analysis on the DNAs extracted from parental bloods revealed a 402-kb 15q11.2 microdeletion or arr 15q11.2 (22,815,577-23,217,514) × 1.0 (hg19) encompassing TUBGCP5, CYFIP1, NIPA2 and NIPA1 in the phenotypically normal father. The mother did not have any genomic imbalance. Level II ultrasound at 21 weeks of gestation revealed microcephaly and IUGR. The parents elected to terminate the pregnancy at 22 weeks of gestation, and a female fetus was delivered with a body weight of 448 g (10th centile) and a body length of 26 cm (3rd-10th centile) but no gross abnormalities.

CONCLUSION

Fetuses with a 15q11.2 (BP1-BP2) microdeletion may present ventriculomegaly, microcephaly and IUGR on prenatal ultrasound, and aCGH is helpful for prenatal diagnosis under such a circumstance.

Prenatal microarray analysis in right aortic arch-a retrospective cohort study and review of the literature

OBJECTIVE

To examine the risk for clinically significant chromosomal microarray analysis (CMA) findings in fetal right aortic arch (RAA).

METHODS

Data from all CMA analyses performed owing to isolated RAA reported to the Israeli Ministry of Health between January 2013 and September 2016 were evaluated retrospectively. Risk for abnormal CMA findings was compared with two control populations, based on both previously described 9272 pregnancies with normal ultrasound, and on a local cohort of 5541 pregnancies undergoing CMA testing owing to maternal request. In addition, Pubmed database search was conducted for original researches examining this issue.

RESULTS

Of 94 CMA analyses performed owing to isolated RAA, six (6.4%) pathogenic findings were detected (47,XX + 21; 45,X; two 22q11.2 microdeletions; 10p15.3 microdeletion and 16p11.2 duplication). Compared with control groups, an isolated RAA yielded a significantly increased relative risk for abnormal CMA results. Literature search yielded two additional retrospective studies describing microarray testing in RAA and encompassing 57 cases. The overall risk for clinically significant CMA findings was 6.62% (10/151).

CONCLUSIONS

CMA testing is indicated in cases of prenatal isolated RAA, even in the era of advanced sonographic equipment, routine biochemical screening for Down syndrome and available non-invasive prenatal testing.