Prenatal ultrasound findings, genetic testing, and literature review of Isolated left subclavian artery.

BACKGROUND: The occurrence of Isolated left subclavian artery (ILSA) is relatively rare, ILSA is caused by the persistence of the dorsal segment of the sixth left arch, with regression of the fourth arch artery and interruption of the left dorsal aorta at the distal end of the seventh intersegmental artery on the left side during embryonic development. The left subclavian artery is connected to the pulmonary artery through an arterial duct, which can be closed or unobstructed. This abnormality can lead to congenital subclavian steal syndrome and vertebrobasilar artery insufficiency. CASE PRESENTATION: We reported three fetuses with ILSA and intracardiac malformation. Among them, one case was suspected to be diagnosed with ILSA by echocardiography, while the other two cases were not diagnosed, but were accidentally discovered during autopsy. We have also conducted a literature review of its prenatal screening, diagnosis, management, and outcomes. Our three cases were tested by WES-Trio (whole exome sequencing). Worldwide, the ILSA cases reported in English literature have not been detected by WES. And likely pathogenic results were found in our two cases. Although it could not explain the intracardiac malformation we found, it will help to explore the etiology in the future. CONCLUSIONS: Prenatal echocardiography detection and diagnosis of ILSA is a new challenge, which has different effects on the prognosis of the fetus. When finding intracardiac malformation with right aortic arch, we need to perform an unconventional view of ultrasound scanning and combine with CDFI to find the origin of the left subclavian artery. Although we cannot find the cause of the disease temporarily, but our genetic results can help prenatal genetic counseling.

Prenatal genetic analysis of fetal aberrant right subclavian artery with or without additional ultrasound anomalies in a third level referral center.

To evaluate the correlation between chromosomal abnormalities and fetal aberrant right subclavian artery (ARSA) with or without additional ultrasound anomalies (UAs). A total of 340 fetuses diagnosed with ARSA by ultrasound between December, 2015, and July, 2021, were included. All cases were subdivided into three groups: (A) 121 (35.6%) cases with isolated ARSA, (B) 91 (26.8%) cases with soft markers, and (C) 128 (37.6%) cases complicated with other UAs. Invasive testing was performed via amniotic fluid or cord blood karyotyping and chromosomal microarray analysis (CMA) in parallel, and pregnancy outcomes were followed. Karyotype abnormalities were identified in 18/340 (5.3%) patients. Karyotype abnormalities in Groups A, B, and C were 0/121 (0.0%), 7/91 (7.7%), and 11/128 (8.6%), respectively. CMA abnormalities with clinically significant variants were detected in 37/340 (10.9%) cases, of which 22q11.2 deletion syndrome and trisomy 21 accounted for 48.6% (18/37). The overall abnormal CMA with clinically significant variant detection rates in Groups A, B, and C were 3/121(2.5%), 13/91 (14.3%), and 21/128 (16.4%), respectively. There were significant difference in clinically significant CMA anomalies detection rate between Groups A and C (p < 0.05), as well as Groups A and B (p < 0.05). Comparing CMA to karyotyping showed a clinically significant incremental yield in Group C (7.8%, 10/128) compared to Groups A (2.5%, 3/121) and B (6.6%, 6/91) (p > 0.05). Fetal ARSA with additional UAs, concurred with cardiac and extra-cardiac anomalies, constitutes a high-risk factor for chromosomal aberrations, especially for pathogenic or likely pathogenic copy number variants.

Hajdu-Cheney syndrome with atypical cardiovascular abnormalities.

Hajdu-Cheney syndrome is an ultra-rare autosomal dominant disorder caused by a heterozygous variant in NOTCH2 gene. Characteristic features include osteolysis, distinct facial appearance, skull deformity, joint laxity, osteoporosis, and short stature. Associated abnormalities are congenital heart disease, congenital defects of the kidney, and neurological problems. Here, we present the first reported case of an African child with a variant in NOTCH2 gene and features of Hajdu-Cheney syndrome in whom we detected a congenital heart defect that has not been previously reported in association with the syndrome. To appropriately characterize this disease and document correct proportion of cardiovascular malformation associations, echocardiography is recommended for all cases of Hajdu Cheney syndrome.

Prenatal Diagnosis of Aberrant Right Subclavian Artery: Association with Genetic Abnormalities.

OBJECTIVE: The objective of the present study was to determine the frequency of malformations and chromosomal abnormalities in a population of fetuses with an aberrant right subclavian artery (ARSA). METHODS: This is a 6-year retrospective study of fetuses with a prenatal diagnosis of ARSA conducted during the period between September 2013 and June 2019 at a fetal medicine unit. Data were collected from ultrasound, fetal echocardiograms, genetic studies, and neonatal records. RESULTS: An ARSA was diagnosed in 22 fetuses. An ARSA was an isolated finding in 18 out of 22 cases (82%). Associated abnormal sonographic findings were found in 4 cases. All cases underwent invasive testing. In 1 of the cases, a chromosomal abnormality was detected (mos 45,X [13]/46,X,e(X) (p22.1q22.1)). No cases of congenital heart disease were found in any of these fetuses. There were two cases in which the postnatal evaluation revealed a malformation: one case of hypospadias and 1 case of cleft palate. CONCLUSION: The presence of an isolated ARSA is benign and is not associated with chromosomal abnormalities. The finding of ARSA, however, warrants a detailed fetal ultrasound in order to exclude major fetal abnormalities and other soft markers.

OBJETIVO: O objetivo do presente estudo foi determinar a frequência de malformaçães e anomalias cromossômicas em uma população de fetos com artéria subclávia direita aberrante (ARSA). MéTODOS: Este é um estudo retrospectivo de 6 anos de fetos com diagnóstico pré-natal de ARSA realizado durante o período de setembro de 2013 a junho de 2019 em uma unidade de medicina fetal. Os dados foram coletados de ultrassom, ecocardiograma fetal, estudos genéticos e registros neonatais. RESULTADOS: Um ARSA foi diagnosticado em 22 fetos. Um ARSA foi um achado isolado em 18 dos 22 casos (82%). Achados ultrassonográficos anormais associados foram encontrados em 4 casos. Todos os casos foram submetidos a testes invasivos. Em um dos casos, foi detectada uma anormalidade cromossômica (mos 45, X [13] / 46, X, e (X) (p22.1q22.1)). Nenhum caso de doença cardíaca congênita foi encontrado em qualquer um desses fetos. Houve dois casos em que a avaliação pós-natal revelou a malformação: um caso de hipospádia e 1 caso de fenda palatina. CONCLUSãO: A presença de ARSA isolado é benigna e não está associada a anormalidades cromossômicas. O achado de ARSA, no entanto, justifica uma ultrassonografia fetal detalhada para excluir anormalidades fetais importantes e outros marcadores leves.

Prenatal Diagnosis of Aberrant Right Subclavian Artery: Association with Genetic Abnormalities / Diagnóstico pré-natal de artéria subclávia direita anômala: associação com anormalidades genéticas

Abstract Objective The objective of the present study was to determine the frequency of malformations and chromosomal abnormalities in a population of fetuses with an aberrant right subclavian artery (ARSA). Methods This is a 6-year retrospective study of fetuses with a prenatal diagnosis of ARSA conducted during the period between September 2013 and June 2019 at a fetal medicine unit. Data were collected from ultrasound, fetal echocardiograms, genetic studies, and neonatal records. Results An ARSA was diagnosed in 22 fetuses. An ARSA was an isolated finding in 18 out of 22 cases (82%). Associated abnormal sonographic findings were found in 4 cases. All cases underwent invasive testing. In 1 of the cases, a chromosomal abnormality was detected (mos 45,X [13]/46,X,e(X) (p22.1q22.1)). No cases of congenital heart disease were found in any of these fetuses. There were two cases in which the postnatal evaluation revealed amalformation: one case of hypospadias and 1 case of cleft palate. Conclusion The presence of an isolated ARSA is benign and is not associated with chromosomal abnormalities. The finding of ARSA, however, warrants a detailed fetal ultrasound in order to exclude major fetal abnormalities and other soft markers.

Resumo Objetivo O objetivo do presente estudo foi determinar a frequência demalformaçães e anomalias cromossômicas em uma população de fetos com artéria subclávia direita aberrante (ARSA). Métodos Este é um estudo retrospectivo de 6 anos de fetos com diagnóstico prénatal de ARSA realizado durante o período de setembro de 2013 a junho de 2019 em uma unidade de medicina fetal. Os dados foram coletados de ultrassom, ecocardiograma fetal, estudos genéticos e registros neonatais. Resultados Um ARSA foi diagnosticado em 22 fetos. Um ARSA foi um achado isolado em 18 dos 22 casos (82%). Achados ultrassonográficos anormais associados foram encontrados em 4 casos. Todos os casos foram submetidos a testes invasivos. Em um dos casos, foi detectada uma anormalidade cromossômica (mos 45, X [13] / 46, X, e (X) (p22.1q22.1)). Nenhum caso de doença cardíaca congênita foi encontrado em qualquer um desses fetos. Houve dois casos em que a avaliação pós-natal revelou a malformação: um caso de hipospádia e 1 caso de fenda palatina. Conclusão A presença de ARSA isolado é benigna e não está associada a anormalidades cromossômicas. O achado de ARSA, no entanto, justifica uma ultrassonografia fetal detalhada para excluir anormalidades fetais importantes e outros marcadores leves.

mTOR deletion in neural crest cells disrupts cardiac outflow tract remodeling and causes a spectrum of cardiac defects through the mTORC1 pathway.

A critical cell type participating in cardiac outflow tract development is a subpopulation of the neural crest cells, the cardiac neural crest cells (NCCs), whose defect causes a spectrum of cardiovascular abnormalities. Accumulating evidence indicates that mTOR, which belongs to the PI3K-related kinase family and impacts multiple signaling pathways in a variety of contexts, plays a pivotal role for NCC development. Here, we investigated functional roles of mTOR for cardiac neural crest development using several lines of mouse genetic models. We found that disruption of mTOR caused NCC defects and failure of cardiac outflow tract separation, which resulted in a spectrum of cardiac defects including persistent truncus arteriosus, ventricular septal defect and ventricular wall defect. Specifically, mutant neural crest cells showed reduced migration into the cardiac OFT and prematurely exited the cell cycle. A number of critical factors and fundamental signaling pathways, which are important for neural crest and cardiomyocyte development, were impaired. Moreover, actin dynamics was disrupted by mTOR deletion. Finally, by phenotyping the neural crest Rptor and Rictor knockout mice respectively, we demonstrate that mTOR acts principally through the mTORC1 pathway for cardiac neural crest cells. Altogether, these data established essential roles of mTOR for cardiac NCC development and imply that dysregulation of mTOR in NCCs may underline a spectrum of cardiac defects.

Report of a novel variant in the FAM111A gene in a fetus with multiple anomalies including gracile bones, hypoplastic spleen, and hypomineralized skull.

Kenny-Caffey syndrome type 2 (KCS2) and osteocraniostenosis (OCS) are allelic disorders caused by heterozygous pathogenic variants in the FAM111A gene. Both conditions are characterized by gracile bones, characteristic facial features, hypomineralized skull with delayed closure of fontanelles and hypoparathyroidism. OCS and KCS2 are often referred to as FAM111A-related syndromes as a group; although OCS presents with a more severe, perinatal lethal phenotype. We report a novel FAM111A mutation in a fetus with poorly ossified skull, proportionate long extremities with thin diaphysis, and hypoplastic spleen consistent with FAM111A-related syndromes. Trio whole exome sequencing identified a p.Y562S de novo missense variant in the FAM111A gene. The variant shows significant similarity to other reported pathogenic mutations fitting proposed pathophysiologic mechanism which provide sufficient evidence for classification as likely pathogenic. Our report contributed a novel variant to the handful of OCS and KCS2 cases reported with pathogenic variants.

Congenital polyvalvular disease expands the cardiac phenotype of the RASopathies.

The RASopathies are a group of similar genetic syndromes with cardiovascular abnormalities, characteristic facial features, short stature, abnormalities of the skin and musculoskeletal system, and variable neurodevelopmental challenges. The most common cardiovascular abnormalities include pulmonary valvular stenosis and hypertrophic cardiomyopathy. Congenital polyvalvular disease (CPVD) refers to congenital dysplasia of two or more cardiac valves. We diagnosed a RASopathy in two individuals with CPVD and noted that CPVD in RASopathies has rarely been reported in the literature. Thus, we performed a retrospective chart review and literature review to investigate the association and characterize the phenotype of CPVD in the RASopathies. CPVD was present in 2.5% (n = 6/243) of individuals in our RASopathy cohort. Involvement of two cardiac valves, commonly the aortic and pulmonic valves, was seen in the majority of individuals (6/8; 75%) in our cohort, but only 27% (3/11) of reported CPVD and RASopathy cases in the literature. CPVD should be considered an associated cardiovascular phenotype of the RASopathies, which has implications for diagnosis and management.

Prenatal features, associated co-morbidities and clinical course of agenesis of the ductus venosus in the current era.

OBJECTIVES: Agenesis of the ductus venosus (ADV) has been associated with additional anomalies in up to 83% of cases. We sought to investigate characteristics, co-morbidities and outcomes of ADV in the current era. We hypothesized that rates of cardiac and non-cardiac diagnoses and survival would be higher, due to advances in genetic testing, prenatal diagnosis and surveillance. METHODS: A retrospective series of cases diagnosed at our institution from 2007 to 2018 were identified by searching our database. Cardiac and obstetric charts were reviewed for cardiac and extra-cardiac anomalies, genetic results and outcomes. RESULTS: Fourteen cases were diagnosed at a mean gestational age of 23.9 weeks (range 13-33). All had associated genetic, cardiac or extra-cardiac anomalies. Eight (57%) had cardiac anomalies and one other developed cardiomyopathy by 6 months. Extra-cardiac anomalies were present in 93% (13/14) and genetic diagnoses made in 75% (6/8) of those tested. Cardiac output Z-scores were >2 in 60% (6/10) prior to delivery. Two had hydrops, there was one intra-uterine death, 13 live-births and two neonatal deaths. CONCLUSION: Our cohort had more associated diagnoses and a lower mortality than previously reported. In our experience, high output occurs frequently, however with a relatively low risk of hydrops and intrauterine death.

Heritability of haemodynamics in the ascending aorta.

Blood flow in the vasculature can be characterised by dimensionless numbers commonly used to define the level of instabilities in the flow, for example the Reynolds number, Re. Haemodynamics play a key role in cardiovascular disease (CVD) progression. Genetic studies have identified mechanosensitive genes with causal roles in CVD. Given that CVD is highly heritable and abnormal blood flow may increase risk, we investigated the heritability of fluid metrics in the ascending aorta calculated using patient-specific data from cardiac magnetic resonance (CMR) imaging. 341 participants from 108 British Caucasian families were phenotyped by CMR and genotyped for 557,124 SNPs. Flow metrics were derived from the CMR images to provide some local information about blood flow in the ascending aorta, based on maximum values at systole at a single location, denoted max, and a 'peak mean' value averaged over the area of the cross section, denoted pm. Heritability was estimated using pedigree-based (QTDT) and SNP-based (GCTA-GREML) methods. Estimates of Reynolds number based on spatially averaged local flow during systole showed substantial heritability ([Formula: see text], [Formula: see text]), while the estimated heritability for Reynolds number calculated using the absolute local maximum velocity was not statistically significant (12-13%; [Formula: see text]). Heritability estimates of the geometric quantities alone; e.g. aortic diameter ([Formula: see text], [Formula: see text]), were also substantially heritable, as described previously. These findings indicate the potential for the discovery of genetic factors influencing haemodynamic traits in large-scale genotyped and phenotyped cohorts where local spatial averaging is used, rather than instantaneous values. Future Mendelian randomisation studies of aortic haemodynamic estimates, which are swift to derive in a clinical setting, will allow for the investigation of causality of abnormal blood flow in CVD.

Macrophage Depletion Improves Endothelial Insulin Resistance and Protects against Cardiovascular Injury in Salt-Sensitive Hypertension.

Vascular endothelial insulin signaling is critical for the maintenance of vascular and metabolic homeostasis. We have previously shown that in hypertensive Dahl rats, impaired vascular insulin action is linked to angiotensin II activation of the NFκB inflammatory pathway. Macrophage polarization (M1) has implicated in hypertensive and metabolic diseases. Here, we investigated the effect of macrophage depletion using liposome-encapsulated clodronate (LEC) on endothelial insulin resistance and cardiovascular remodeling in Dahl salt-sensitive (DS) rats. High salt intake (HS) for 5 weeks increased systolic blood pressure (SBP: 192 ± 5 vs. 144 ± 4 mmHg in NS, p < 0.05), aortic and cardiac hypertrophy, cardiac fibrosis, and impaired acetylcholine- and insulin-induced vasorelaxation, accompanied by impaired insulin activation of endothelial nitric oxide synthases (eNOS)/NO signaling. HS rats had a significant increase in CD68 (a monocyte/macrophage marker) expression in the aorta and the heart. LEC reduced SBP (168 ± 5 mmHg, p < 0.05) and cardiovascular injury and improved acetylcholine- and insulin-mediated vasorelaxation and insulin signaling molecules with a reduction in the macrophage infiltration in the aorta and the heart. HS rats also manifested an increase in the aortic expressions of inflammatory cytokines, including the ratio of phosphorylated inhibitory kappa B (Iκb)/Iκb, tumor necrosis factor α, and phosphorylated c-Jun N-terminal kinase (JNK) and oxidative stress, which were reduced in HS/LEC rats. Our results suggest that in salt-sensitive hypertension, macrophage may importantly contribute to endothelial insulin resistance, vascular inflammation, and injury. These findings support the idea that macrophages may be a new target for immunotherapy of vasculopathy in hypertensive and metabolic disorders.

Associated anomalies in cases with congenital clubfoot.

Congenital clubfoot CTEV is a common congenital anomaly, its etiology is unclear and its pathogenesis is controversial. Cases with CTEV often have other non-CTEV associated congenital anomalies. The purpose of this study was to assess the prevalence and the types of these associated anomalies in a defined population. The associated anomalies in cases with CTEV were collected in all livebirths, stillbirths, and terminations of pregnancy during 29 years in 387,067 consecutive births in the area covered by our population-based registry of congenital malformations. Of the 504 cases with CTEV, representing a prevalence of 13.02 per 10,000, 107 (21.2%) had associated anomalies. There were 31 (6.1%) cases with chromosomal abnormalities, and 21 (4.2%) non-chromosomal recognized dysmorphic conditions including syndromes: 6 arthrogryposis multiplex congenita, 2 22q11.2 microdeletion, and one fetal alcohol syndrome. Fifty-five (10.9%) of the cases had nonsyndromic multiple congenital anomalies (MCA). Anomalies in the cardiovascular, the central nervous, the urinary, the orofacial, and the musculoskeletal systems were the most common other anomalies in the cases with MCA. The anomalies associated with CTEV could be classified into a recognizable malformation syndrome in 52 of the 107 cases (48.6%) with associated anomalies. This study included special strengths: it is population-based, each affected child was examined by a geneticist, all elective terminations were ascertained, and the surveillance for anomalies was continued until 2 years of age. In conclusion the overall prevalence of associated anomalies, one of five cases, emphasizes the need for a screening for other anomalies in cases with CTEV.

Prenatal diagnosis of a de novo tetrasomy 15q24.3-25.3: Case report and literature review.

BACKGROUND: Terminal duplication on chromosome 15q is a rare chromosomal variation. Affected individuals show similar features such as growth dysplasia or the development of frontal bossing, body deformities, facial abnormalities, and genitourinary or cardiovascular disorders. However, it is not yet clear whether such 15q repeats lead to identifiable patterns of clinical abnormalities. Therefore, the purpose of this study was to analyze the prenatal diagnostic results and clinical manifestations of a fetus with 15q duplication and to summarize the literature. METHODS: The case was a fetus at 28 weeks of gestation. The risk of Down syndrome from second-trimester screening was 1/140. Prenatal ultrasound and amniocentesis were performed, and chromosomal microarray analysis (CMA) was used for genetic analysis. RESULTS: The fetus had abnormal clinical features, including intracardiac echogenic focus in the left ventricle, an aberrant right subclavian artery, and growth delay. The fetal chromosomal karyotype was 46,XX,15q?,12q?,21pstk+, and CMA revealed a 10.163 Mb duplication at 15q24.3-q25.3. The couple chose to terminate the pregnancy after careful consideration. CONCLUSIONS: The combination and rational application of cytogenetics technology and molecular genetics technology such as CMA will open up the field of clinical application and provide useful genetic counseling for parents of fetuses carrying such chromosomal duplications.

A case of G1013R FBN1 mutation: A potential genotype-phenotype correlation in severe Marfan syndrome.

Marfan Syndrome (MFS) is an autosomal dominant connective tissue disorder with a wide range of severities. Ninety-five percent of MFS probands have a mutation in the fibrillin-1 gene (FBN1); however, there are a high number of unique mutations complicating attempts at establishing any phenotype-genotype correlations for this disease (Tiecke et al., European Journal of Human Genetics, 2001, 9, 13-21). One of the few extant genotype-phenotype correlations is in exon 24-32 which have been associated with a severe pediatric presentation of neonatal MFS with predominately cardiovascular symptoms. We present a 24-year-old male patient with a heterozygous de novo variant NM_000138.4: c.3037G>A (p.G1013R) located in exon 25 of the FBN1 gene. The patient was found to have dysplastic mitral and tricuspid valves with dilated aortic root at 9 months of age. This is a notable case in that the location of this patient's mutation and his age of symptom onset would indicate a guarded prognosis. Further, this mutation, FBN1 G1013R, has been reported in the literature in four other unrelated patients all of whom presented at a young age with cardiac involvement and all of whom had relative longevity when compared to other patients with mutations in this exon 24-32 hot spot. These findings may represent a more specific genotype-phenotype correlation within this mutational hot spot.

Discordance of cardiovascular abnormalities in a monozygotic twin pair carrying a class II 1q21.1 microdeletion.

OBJECTIVE: We present the prenatal diagnosis of a class II 1q21.1 microdeletion in monozygotic (MZ) twins with discordant phenotypes. CASE REPORT: A monochorionic diamniotic twin pair presented with discordant ultrasound anomalies; twin A had cardiovascular abnormalities, while twin B did not. No specific complications were noted in the twins during pregnancy. A single nucleotide polymorphism array revealed an identical class II 1q21.1 microdeletion inherited from a phenotypically normal mother and identified the twins as MZ. The deleted region encompassed both the proximal 1q21.1 thrombocytopenia absent radius syndrome region and the distal 1q21.1 recurrent microdeletion region. No other rare copy number variants (CNVs) were identified, and concordance was observed in the CNVs between the twins. CONCLUSION: Discordant cardiovascular abnormalities may occur in MZ twins carrying the same class II 1q21.1 microdeletion. Further studies involving discordant MZ twins are needed to determine the modifying factors of the phenotypic heterogeneity of the microdeletion.

PRENATAL IDENTIFICATION OF ABERRANT RIGHT SUBCLAVIAN ARTERY IN ISOLATION: THE NEED FOR FURTHER GENETIC WORK-UP?

The objective of this study was to evaluate the association between aberrant right subclavian artery (ARSA) and chromosomal abnormalities. The study included 5211 women having attended our unit for fetal anatomic screening and fetal echocardiography from August 2016 until February 2019. After diagnosing ARSA, prenatal invasive testing was discussed with the patients. ARSA affected fetus was determined in 57 cases; of these, there were 38 cases of isolated ARSA and 19 cases of non-isolated ARSA but associated with soft markers and fetal anomalies. Nineteen patients underwent amniocentesis; Down syndrome was determined in two women, both of them from the non-isolated ARSA group, with fetal hydrops, atrioventricular septal defect and esophageal atresia. Fifteen of 38 patients who declined prenatal diagnostic testing, accepted karyotype analysis after delivery and none of these 15 cases had chromosomal abnormalities. Identification of ARSA should be followed by detailed ultrasound examination to ensure that there are no accompanying soft markers and/or structural defects. Isolated ARSA may not be an indication for karyotype analysis or 22q11.2 microdeletions. Non-ARSA implies a strong predictor of aneuploidy, and when additional findings are detected, invasive testing should be offered to the parents. The association between isolated ARSA and genetic disease should be evaluated in large powered prospective studies.

Genome-wide association studies of structural birth defects: A review and commentary.

BACKGROUND: While there is strong evidence that genetic risk factors play an important role in the etiologies of structural birth defects, compared to other diseases, there have been relatively few genome-wide association studies (GWAS) of these conditions. We reviewed the current landscape of GWAS conducted for birth defects, noting novel insights, and future directions. METHODS: This article reviews the literature with regard to GWAS of structural birth defects. Key defects included in this review include oral clefts, congenital heart defects (CHDs), biliary atresia, pyloric stenosis, hypospadias, craniosynostosis, and clubfoot. Additionally, other issues related to GWAS are considered, including the assessment of polygenic risk scores and issues related to genetic ancestry, as well as utilizing genome-wide single nucleotide polymorphism array data to evaluate gene-environment interactions and Mendelian randomization. RESULTS: For some birth defects, including oral clefts and CHDs, several novel susceptibility loci have been identified and replicated through GWAS, including 8q24 for oral clefts, DGKK for hypospadias, and 4p16 for CHDs. Relatively common birth defects for which there are currently no published GWAS include neural tube defects, anotia/microtia, anophthalmia/microphthalmia, gastroschisis, and omphalocele. CONCLUSIONS: Overall, GWAS have been successful in identifying several novel susceptibility genes and genomic regions for structural birth defects. These findings have provided new insights into the etiologies of these phenotypes. However, GWAS have been underutilized for understanding the genetic etiologies of several birth defects.

Novel homozygous ENPP1 mutation causes generalized arterial calcifications of infancy, thrombocytopenia, and cardiovascular and central nervous system syndrome.

Generalized arterial calcifications of infancy (GACI) is caused by mutations in ENPP1. Other ENPP1-related phenotypes include pseudoxanthoma elasticum, hypophosphatemic rickets, and Cole disease. We studied four children from two Bedouin consanguineous families who presented with severe clinical phenotype including thrombocytopenia, hypoglycemia, hepatic, and neurologic manifestations. Initial working diagnosis included congenital infection; however, patients remained without a definitive diagnosis despite extensive workup. Consequently, we investigated a potential genetic etiology. Whole exome sequencing (WES) was performed for affected children and their parents. Following the identification of a novel mutation in the ENPP1 gene, we characterized this novel multisystemic presentation and revised relevant imaging studies. Using WES, we identified a novel homozygous mutation (c.556G > C; p.Gly186Arg) in ENPP1 which affects a highly conserved protein domain (somatomedin B2). ENPP1-associated genetic diseases exhibit phenotypic heterogeneity depending on mutation type and location. Follow-up clinical characterization of these families allowed us to revise and detect new features of systemic calcifications, which established the diagnosis of GACI, expanding the phenotypic spectrum associated with ENPP1 mutations. Our findings demonstrate that this novel ENPP1 founder mutation can cause a fatal multisystemic phenotype, mimicking severe congenital infection. This also represents the first reported mutation affecting the SMB2 domain, associated with GACI.

Co-exposure to an Aryl Hydrocarbon Receptor Endogenous Ligand, 6-Formylindolo[3,2-b]carbazole (FICZ), and Cadmium Induces Cardiovascular Developmental Abnormalities in Mice.

6-Formylindolo[3,2-b]carbazole (FICZ) is a signal substance and an endogenous activator of aryl hydrocarbon receptor (AHR). Cadmium (Cd) is an environmental pollutant that can activate both AHR and Wnt/ß-catenin signaling pathways. We aimed to determine how dysregulated signaling through AHR-Wnt/ß-catenin cross-talk can influence mice heart development. Mice fetuses were exposed to Cd alone or in combination with FICZ in gestation day (GD) 0. In GD18, fetuses were harvested and randomly divided into two parts for stereological and molecular studies. Stereological and tessellation results revealed that when fetuses were co-exposed with FICZ and Cd, abnormalities were synergistically raised. In the presence of FICZ, mRNA expression levels of Wnt/ß-catenin target genes significantly enhanced, especially when animals co-treated with FICZ and Cd. Based on these findings, we propose that chemical pollutants can interfere with the normal function of AHR that has a physiological role in regulating Wnt/ß-catenin during cardiogenesis.