Persistently elevated nuchal translucency and the fetal heart

The Incidence of the Agenesis of Fetal Ductus Venosus at the 11-13 Weeks' Ultrasound Examination

OBJECTIVE

The objective is to examine the incidence of agenesis of fetal ductus venosus (DV) at the routine ultrasound examination at 11-13 weeks.

MATERIALS AND METHODS

This is a retrospective study on women presenting for screening for chromosomal abnormalities. The fetal DV was routinely examined by color Doppler in the sagittal view.

RESULTS

Out of 8,304 fetuses examined, there were 13 cases of DV agenesis (0.15%). The umbilical vein drainage was intra-hepatic in two-thirds of the cases, and all resulted in normal live births. In the remaining one-third of cases, the umbilical vein drained to the inferior vena cava and all had a poor outcome because of aneuploidies, cardiac defects, and Noonan syndrome.

CONCLUSION

Fetal DV agenesis occurs in about one in 650 fetuses and the majority of cases have a benign course and a favorable outcome. Failure to identify the DV should prompt a detailed ultrasound examination, identification of the drainage site of the umbilical vein, and genetic testing.

Clinical presentation, genetic etiology and outcome associated with fetal cardiomyopathy: comparison of two eras

OBJECTIVE

To assess the rate and type of genetic diagnosis and clinical outcome of cases of fetal cardiomyopathy (CM) during two eras, in order to examine the impact of advanced genetic testing and improved perinatal management strategies.

METHODS

All diagnoses of fetal CM in Alberta, Canada, encountered between 2003 and 2019, were reviewed retrospectively. Genetic, cardiac and non-cardiac diagnoses and clinical outcome were documented. Cases with CM secondary to extracardiac pathology and maternal conditions were excluded. Cases diagnosed in the earlier era of the study period (2003-2012) were compared with those diagnosed in the later era (2013-2019).

RESULTS

Thirty-eight cases of fetal CM met the inclusion criteria. Median gestational age (GA) at diagnosis was 22.8 (range, 13.4-37.4) weeks. Associated structural heart disease was present in 39% (15/38) of cases and 24% (9/38) had arrhythmia. Hydrops was identified in 29% (11/38) of cases at presentation, and a further 18% (7/38) developed hydrops later in gestation. Twenty-six percent (10/38) of cases underwent termination of pregnancy and 24% (9/38) had intrauterine death. Of liveborn cases, neonatal death occurred in 16% (3/19), late death occurred in 21% (4/19) and 63% (12/19) were alive at the last follow-up. Excluding cases that had termination of pregnancy and those with a liveborn infant who received planned palliative care, the rate of neonatal survival was higher in the later compared with the earlier era (69% (11/16) vs 45% (5/11)), although the difference was not statistically significant (P = 0.26). A genetic etiology was confirmed in 39% (15/38) of cases and strongly suspected in 24% (9/38). A significantly higher proportion of cases had a confirmed or strongly suspected genetic etiology in the later era compared with in the earlier era (76% (19/25) vs 38% (5/13); P = 0.04).

CONCLUSIONS

In the recent era, a higher proportion of fetal CM cases had a confirmed or strongly suspected genetic etiology than reported previously. Based on comparison with older series, modern perinatal management strategies may not have a significant impact on neonatal survival in cases of fetal CM; however, a larger study would be better powered to detect more subtle differences. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Lymphatic Abnormalities in Noonan Syndrome Spectrum Disorders: A Systematic Review

Noonan syndrome spectrum disorders are a group of phenotypically related conditions, resembling Noonan syndrome, caused by germline pathogenic variants in genes within the Ras/mitogen-activated protein kinase (Ras/MAPK) signalling pathway. Lymphatic dysplasia with a clinical lymphatic abnormality is one of the major features. We performed a systematic review to get more insight in (1) the prevalence of clinically lymphatic abnormalities in patients with a genetically proven Noonan syndrome spectrum disorder, (2) if a genotype-lymphatic phenotype relation can be found and describe the clinical presentation and course of the lymphatic abnormality. Most studies report patients with Noonan syndrome. Prenatally, the prevalence of increased nuchal translucency differs from 7% in patients with pathogenic PTPN11 variants to 38% in patients with pathogenic RIT1 variants, and the prevalence of pleural effusions differed from 7% in patients with pathogenic SOS1 to 29% in patients with pathogenic RIT1 variants. Postnatally, the prevalence of lymphedema differs from 16% in patients with pathogenic PTPN11 variants to 44% in patients with pathogenic SOS1 variants, and the prevalence of acquired chylothorax is 4% in patients with pathogenic RIT1 variants. Lymphatic abnormalities do occur in patients with cardiofaciocutaneous syndrome and Costello syndrome. In conclusion, Noonan syndrome spectrum disorders, Noonan syndrome in particular, are associated with lymphatic abnormalities. Combining the available published literature about genetically proven Noonan syndrome spectrum disorders, it appears likely that the lifetime prevalence of these abnormalities in Noonan syndrome is higher than the 20% that were generally accepted so far. This is increasingly important, because the activation of the RAS/MAPK pathway can be inhibited by RAS/MAPK inhibitors, and clinically severe lymphatic abnormalities may improve.

Microarray and RASopathy-disorder testing in fetuses with increased nuchal translucency

OBJECTIVES

To determine the incidence of chromosomal abnormalities, submicroscopic chromosomal abnormalities and RASopathy-disorder (RD) pathogenic variants in a cohort of pregnancies with nuchal translucency thickness (NT) ≥ 3.5 mm, and to propose a clinical protocol for surveillance of this group of patients.

METHODS

This was a retrospective chart review of patients referred to The Prenatal Diagnosis and Medical Genetics Program at Mount Sinai Hospital between January 2013 and December 2015, due to NT ≥ 3.5 mm, who underwent chorionic villus sampling or amniocentesis. Patients underwent extensive genetic counseling prior to invasive procedures and testing. Quantitative fluorescence polymerase chain reaction (QF-PCR) was performed as the first-line test for aneuploidy. If the result was negative, patients underwent karyotyping and/or chromosomal microarray analysis (CMA), and if the findings were normal, they had testing for RD pathogenic variants, which included nine known genes. Patients also underwent detailed fetal ultrasound examinations and echocardiography, performed by expert operators.

RESULTS

A total of 226 eligible patients were identified. In 116/226 (51.3%) patients, QF-PCR identified a chromosomal aneuploidy. The remaining 110/226 (48.7%) patients had further genetic testing. Karyotyping/CMA detected an abnormal/pathogenic cytogenetic result in 9/110 (8.2%) patients, as well as five variants of unknown significance (VOUS). RD testing yielded three pathogenic variants (3/103), giving a detection rate of 2.9%, and one VOUS. The optimal NT cut-off for RD screening was 7.9 mm in this population. In 92/110 (83.6%) patients, the genetic investigations were normal. Of these pregnancies, an early (14-16 weeks' gestation) detailed fetal ultrasound examination identified a structural abnormality in 24 (26.1%), 15 (16.3%) had an abnormal detailed ultrasound examination at 18-22 weeks' gestation and fetal echocardiography showed a cardiac abnormality in nine (9.8%). The birth outcome in the 83 pregnancies that had normal genetic investigations and known outcome included seven (8.4%) cases of termination of pregnancy, seven (8.4%) cases of intrauterine fetal death and 69 (83.1%) cases of live birth. Nine (9.8%) patients were lost to follow-up.

CONCLUSIONS

Both CMA and molecular testing for RD are important investigations in pregnancies with NT ≥ 3.5 mm. The use of genetic testing combined with fetal ultrasound examination provides valuable information that can influence pregnancy outcome, and provide recurrence risks, in this patient population. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Genetic Basis for Congenital Heart Disease: Revisited: A Scientific Statement From the American Heart Association

This review provides an updated summary of the state of our knowledge of the genetic contributions to the pathogenesis of congenital heart disease. Since 2007, when the initial American Heart Association scientific statement on the genetic basis of congenital heart disease was published, new genomic techniques have become widely available that have dramatically changed our understanding of the causes of congenital heart disease and, clinically, have allowed more accurate definition of the pathogeneses of congenital heart disease in patients of all ages and even prenatally. Information is presented on new molecular testing techniques and their application to congenital heart disease, both isolated and associated with other congenital anomalies or syndromes. Recent advances in the understanding of copy number variants, syndromes, RASopathies, and heterotaxy/ciliopathies are provided. Insights into new research with congenital heart disease models, including genetically manipulated animals such as mice, chicks, and zebrafish, as well as human induced pluripotent stem cell-based approaches are provided to allow an understanding of how future research breakthroughs for congenital heart disease are likely to happen. It is anticipated that this review will provide a large range of health care-related personnel, including pediatric cardiologists, pediatricians, adult cardiologists, thoracic surgeons, obstetricians, geneticists, genetic counselors, and other related clinicians, timely information on the genetic aspects of congenital heart disease. The objective is to provide a comprehensive basis for interdisciplinary care for those with congenital heart disease.

Prenatal ultrasound findings of rasopathies in a cohort of 424 fetuses: update on genetic testing in the NGS era

BACKGROUND

This study evaluates 6 years of prenatal rasopathy testing in the Netherlands, updates on previous data and gives recommendations for prenatal rasopathy testing.

METHODS

424 fetal samples, sent in for prenatal rasopathy testing in 2011-2016, were collected. Cohort 1 included 231 samples that were sequenced for 1-5 rasopathy genes. Cohort 2 included 193 samples that were analysed with a 14-gene next generation sequencing (NGS) panel. For all mutation-positive samples in both cohorts, the referring physician provided detailed ultrasound findings and postnatal follow-up. For 168 mutation-negative samples in cohort 2, solely clinical information on the requisition form was collected.

RESULTS

In total, 40 (likely) pathogenic variants were detected (9.4%). All fetuses showed a variable degree of involvement of prenatal findings: increased nuchal translucency (NT)/cystic hygroma, distended jugular lymph sacs (JLS), hydrops fetalis, polyhydramnios, pleural effusion, ascites, cardiac defects and renal anomalies. An increased NT was the most common finding. Eight fetuses showed solely an increased NT/cystic hygroma, which were all larger than 5.5 mm. Ascites and renal anomalies appeared to be poor predictors of pathogenic outcome.

CONCLUSION

Fetuses with a rasopathy show in general multiple ultrasound findings. The larger the NT and the longer it persists, the more likely it is to find a pathogenic variant. Rasopathy testing is recommended when the fetus shows an isolated increased NT ≥5.0 mm or when NT of ≥3.5 mm and at least one of the following ultrasound anomalies is present: distended JLS, hydrops fetalis, polyhydramnios, pleural effusion, ascites, cardiac defects and renal anomalies.