RESUMO
Partial anomalous pulmonary venous connections (PAVC) have been found after abnormal gene expressions involving several syndromes. Total anomalous pulmonary venous connection (TAPVC) is found in conjunction with heterotaxia syndrome as well as several other syndromes. It has been reported with an autosomal dominance with variable expression and incomplete penetrance. The occurrence is also related to environmental factors which may superimpose on a familial susceptibility for TAPVC. Many pathways are involved in the normal development of the pulmonary venous connections and as a consequence disturbance of many genetic and epigenetic pathways lead to partial or total pulmonary venous misconnections. In this chapter, an overview of current knowledge regarding human genetics of anomalous venous connections is provided.
Assuntos
Veias Pulmonares , Síndrome de Cimitarra , Humanos , Síndrome de Cimitarra/genética , Veias Pulmonares/anormalidades , Predisposição Genética para Doença/genética , Síndrome de Heterotaxia/genética , Epigênese GenéticaRESUMO
The venous pole of the heart where the pulmonary veins will develop encompasses the sinus venosus and the atrium. In the fourth week of development, the sinus venosus consists of a left and a right part receiving blood from the common cardinal vein, the omphalomesenteric and umbilical veins. Asymmetrical expansion of the common atrium corresponds with a rightward shift of the connection of the sinus to the atrium. The right-sided part of the sinus venosus including its tributing cardinal veins enlarges to form the right superior and inferior vena cava that will incorporate into the right atrium. The left-sided part in human development largely obliterates and remodels to form the coronary sinus in adults. In approximately the same time window (4th-fifth weeks), a splanchnic vascular plexus surrounds the developing lung buds (putative lungs) with a twofold connection. Of note, during early developmental stages, the primary route of drainage from the pulmonary plexus is toward the systemic veins and not to the heart. After lumenization of the so-called mid-pharyngeal endothelial strand (MPES), the first anlage of the pulmonary vein, the common pulmonary vein can be observed in the dorsal mesocardium, and the primary route of drainage will gradually change toward a cardiac drainage. The splanchnic pulmonary venous connections with the systemic cardinal veins will gradually disappear during normal development. In case of absence or atresia of the MPES, the pulmonary-to-systemic connections will persist, clinically resulting in total anomalous pulmonary venous return (TAPVR). This chapter describes the developmental processes and molecular pathways underlying anomalous pulmonary venous connections.
Assuntos
Veias Pulmonares , Animais , Humanos , Veias Pulmonares/embriologia , Veias Pulmonares/anormalidades , Síndrome de Cimitarra/genética , Síndrome de Cimitarra/embriologia , Modelos Animais de DoençasRESUMO
Anomalous pulmonary venous return (APVR) frequently occurs with other congenital heart defects (CHDs) or extra-cardiac anomalies. While some genetic causes have been identified, the optimal approach to genetic testing in individuals with APVR remains uncertain, and the etiology of most cases of APVR is unclear. Here, we analyzed molecular data from 49 individuals to determine the diagnostic yield of clinical exome sequencing (ES) for non-isolated APVR. A definitive or probable diagnosis was made for 8 of those individuals yielding a diagnostic efficacy rate of 16.3%. We then analyzed molecular data from 62 individuals with APVR accrued from three databases to identify novel APVR genes. Based on data from this analysis, published case reports, mouse models, and/or similarity to known APVR genes as revealed by a machine learning algorithm, we identified 3 genes-EFTUD2, NAA15, and NKX2-1-for which there is sufficient evidence to support phenotypic expansion to include APVR. We also provide evidence that 3 recurrent copy number variants contribute to the development of APVR: proximal 1q21.1 microdeletions involving RBM8A and PDZK1, recurrent BP1-BP2 15q11.2 deletions, and central 22q11.2 deletions involving CRKL. Our results suggest that ES and chromosomal microarray analysis (or genome sequencing) should be considered for individuals with non-isolated APVR for whom a genetic etiology has not been identified, and that genetic testing to identify an independent genetic etiology of APVR is not warranted in individuals with EFTUD2-, NAA15-, and NKX2-1-related disorders.
Assuntos
Anormalidades Múltiplas , Cardiopatias Congênitas , Síndrome de Cimitarra , Animais , Camundongos , Síndrome de Cimitarra/genética , Sequenciamento do Exoma , Anormalidades Múltiplas/genética , Deleção Cromossômica , Testes Genéticos , Cardiopatias Congênitas/diagnóstico , Cardiopatias Congênitas/genética , Proteínas de Ligação a RNA/genéticaRESUMO
Variants in Tbox transcription factor 5 (TBX5) can result in a wide phenotypic spectrum, specifically in the heart and the limbs. TBX5 has been implicated in causing nonsyndromic cardiac defects and HoltOram syndrome (HOS). The present study investigated the underlying molecular etiology of a family with heterogeneous heart defects. The proband had mixedtype total anomalous pulmonary venous return (mixedtype TAPVR), whereas her mother had an atrial septal defect. Genetic testing through triobased wholeexome sequencing was used to reveal the molecular etiology. A nonsense variant was identified in TBX5 (c.577G>T; p.Gly193*) initially showing cosegregation with a presumably nonsyndromic presentation of congenital heart disease. Subsequent genetic investigations and more complete phenotyping led to the correct diagnosis of HOS, documenting the novel association of mixedtype TAPVR with HOS. Finally, protein modeling of the mutant TBX5 protein that harbored this pathogenic nonsense variant (p.Gly193*) revealed a substantial drop in the quantity of noncovalent bonds. The decrease in the number of noncovalent bonds suggested that the resultant mutant dimer was less stable compared with the wildtype protein, consequently affecting the protein's ability to bind DNA. The present findings extended the phenotypic cardiac defects associated with HOS; to the best of our knowledge, this is the first association of mixedtype TAPVR with TBX5. Prior to the current analysis, the molecular association of TAPVR with HOS had never been documented; hence, this is the first genetic investigation to report the association between TAPVR and HOS. Furthermore, it was demonstrated that the nullvariants reported in the Tbox domain of TBX5 were associated with a wide range of cardiac and/or skeletal anomalies on both the interand intrafamilial levels. In conclusion, genetic testing was highlighted as a potentially powerful approach in the prognostication of the proper diagnosis.
Assuntos
Cardiopatias Congênitas , Comunicação Interatrial , Síndrome de Cimitarra , Proteínas com Domínio T , Anormalidades Múltiplas , Feminino , Cardiopatias Congênitas/diagnóstico , Cardiopatias Congênitas/genética , Cardiopatias Congênitas/patologia , Comunicação Interatrial/diagnóstico , Comunicação Interatrial/genética , Humanos , Deformidades Congênitas das Extremidades Inferiores , Fenótipo , Síndrome de Cimitarra/genética , Proteínas com Domínio T/genética , Deformidades Congênitas das Extremidades SuperioresRESUMO
Anomalous pulmonary venous return (APVR) is a potentially lethal congenital heart disease. Elucidating the genetic etiology is crucial for understanding its pathogenesis and improving clinical practice, whereas its genetic basis remains largely unknown because of complex genetic etiology. We thus performed whole-exome sequencing for 144 APVR patients and 1636 healthy controls and report a comprehensive atlas of APVR-related rare genetic variants. Novel singleton, loss-of-function and deleterious missense variants (DVars) were enriched in patients, particularly for genes highly expressed in the developing human heart at the critical time point for pulmonary veins draining into the left atrium. Notably, PLXND1, encoding a receptor for semaphorins, represents a strong candidate gene of APVR (adjusted P = 1.1e-03, odds ratio: 10.9-69.3), accounting for 4.17% of APVR. We further validated this finding in an independent cohort consisting of 82 case-control pairs. In these two cohorts, eight DVars were identified in different patients, which convergently disrupt the GTPase-activating protein-related domain of PLXND1. All variant carriers displayed strikingly similar clinical features, in that all anomalous drainage of pulmonary vein(s) occurred on the right side and incorrectly connected to the right atrium, which may represent a novel subtype of APVR for molecular diagnosis. Studies in Plxnd1 knockout mice further revealed the effects of PLXND1 deficiency on severe heart and lung defects and cellular abnormalities related to APVR such as abnormal migration and vascular formation of vascular endothelial cells. These findings indicate the important role of PLXND1 in APVR pathogenesis, providing novel insights into the genetic etiology and molecular subtyping for APVR.
Assuntos
Cardiopatias Congênitas , Veias Pulmonares , Síndrome de Cimitarra , Animais , Células Endoteliais , Átrios do Coração , Cardiopatias Congênitas/genética , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Glicoproteínas de Membrana , Camundongos , Veias Pulmonares/anormalidades , Síndrome de Cimitarra/genéticaRESUMO
BACKGROUND: Scimitar syndrome is a rare CHD composed of partial anomalous pulmonary venous connection from the right lung, via a scimitar vein, to the inferior vena cava rather than the left atrium. Genetic conditions associated with scimitar syndrome have not been well investigated at present. METHODS: Our study included patients with scimitar syndrome diagnosed at Texas Children's Hospital from January 1987 to July 2020. Medical records were evaluated to determine if genetic testing was performed, including chromosomal microarray analysis or whole-exome sequencing. Copy number variants identified as pathogenic/likely pathogenic and variants of unknown significance were collected. Analyses of cardiac and extracardiac findings were performed via chart review. RESULTS: Ninety-eight patients were identified with scimitar syndrome, 89 of which met inclusion criteria. A chromosome analysis or chromosomal microarray analysis was performed in 18 patients (20%). Whole-exome sequencing was performed in six patients following negative chromosomal microarray analysis testing. A molecular genetic diagnosis was made in 7 of 18 cases (39% of those tested). Ninety-six per cent of the cohort had some type of extracardiac finding, with 43% having asthma and 20% having a gastrointestinal pathology. Of the seven patients with positive genetic testing, all had extracardiac anomalies with all but one having gastrointestinal findings and 30% having congenital diaphragmatic hernia. CONCLUSIONS: Genetic testing revealed an underlying diagnosis in roughly 40% of those tested. Given the relatively high prevalence of pathogenic variants, we recommend chromosomal microarray analysis and whole-exome sequencing for patients with scimitar syndrome and extracardiac defects.
Assuntos
Veias Pulmonares , Síndrome de Cimitarra , Criança , Testes Genéticos , Humanos , Pulmão/anormalidades , Veias Pulmonares/anormalidades , Síndrome de Cimitarra/diagnóstico , Síndrome de Cimitarra/genética , Veia Cava Inferior/anormalidadesRESUMO
A 15q11.2 microdeletion (BP1-BP2) is associated with congenital heart diseases (CHDs), developmental delay, and epilepsy. This deletion co-occurs with CHD in 20-30% patients, but a familial case of CHD and a 15q11.2 deletion has not been identified. Here we report the first familial (three siblings) case of total anomalous pulmonary venous return associated with 15q11.2 deletion. Array comparative genomic hybridization identified a ~395 kb deletion at 15q11.2 in patient 1. This deletion was confirmed by fluorescence in situ hybridization in patients 1 and 3 and their asymptomatic father. No deleterious mutation was identified by proband-only exome sequencing of patient 1. One healthy sibling and their mother did not carry the deletion. This deletion is often inherited from asymptomatic parents with an estimated low penetrance of 10.4%. Conversely, we observed high penetrance of this deletion, but secondary copy-number variants or pathogenic variants were not detected in this family.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 15/genética , Síndrome de Cimitarra/genética , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Síndrome de Cimitarra/patologiaRESUMO
Anomalous pulmonary venous connection (APVC) is an uncommon congenital anomaly in which pulmonary venous blood flows directly into the right side of the heart or into the systemic veins. To identify whether there is any association between 22q11 CNVs and APVC, we analyzed the clinical data of 86 APVC patients and then studied the CNVs of 22q11 in 86 sporadic APVC patients by multiplex ligation-dependent probe amplification. The results showed that two patients carried the CNVs of 22q11, one patient had the deletion of 22q11 and the other had the duplication of 22q11. The incidence was significantly higher than that in the normal population (P < 0.01) that suggests a possible etiologic association between the duplication or deletion of 22q11 and the APVC in our patients.
Assuntos
Deleção Cromossômica , Duplicação Cromossômica , Cromossomos Humanos Par 22/genética , Síndrome de Cimitarra/genética , Criança , Variações do Número de Cópias de DNA , Feminino , Humanos , Masculino , Reação em Cadeia da Polimerase Multiplex , Síndrome de Cimitarra/etiologiaRESUMO
As a rare type of Congenital Heart Defects (CHD), the genetic mechanism of Total Anomalous Pulmonary Venous Return (TAPVR) remains unknown, although previous studies have revealed potential disease-driving regions/genes. Blood samples collected from the 6 sporadic TAPVR cases and 81 non-TAPVR controls were subjected to whole exome sequencing. All detected variations were confirmed by direct Sanger sequencing. Here, we identified 2 non-synonymous missense mutations: c.C652T, p.R218W in activin A receptor type II-like 1 (ACVRL1), c.C717G, p.D239E in sarcoglycan delta (SGCD). Our results offered the landscape of mutations for TAPVR in Chinese population firstly and are valuable in the mutation-based pre- and post-natal screening and genetic diagnosis for TAPVR.
Assuntos
Receptores de Activinas Tipo II/genética , Doenças Raras/genética , Sarcoglicanas/genética , Síndrome de Cimitarra/genética , Adolescente , Povo Asiático/genética , Estudos de Casos e Controles , Criança , Pré-Escolar , Angiografia por Tomografia Computadorizada , Ecocardiografia , Eletrocardiografia , Feminino , Humanos , Lactente , Masculino , Mutação de Sentido Incorreto , Doenças Raras/diagnóstico por imagem , Doenças Raras/cirurgia , Síndrome de Cimitarra/diagnóstico por imagem , Síndrome de Cimitarra/cirurgia , Sequenciamento do ExomaAssuntos
Seio Coronário/anormalidades , Diagnóstico Pré-Natal/métodos , Veias Pulmonares/anormalidades , Síndrome de Cimitarra/diagnóstico , Atrofias Musculares Espinais da Infância/diagnóstico , Seio Coronário/embriologia , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Nascido Vivo , Masculino , Gravidez , Veias Pulmonares/embriologia , Síndrome de Cimitarra/embriologia , Síndrome de Cimitarra/genética , Atrofias Musculares Espinais da Infância/embriologia , Atrofias Musculares Espinais da Infância/genética , Adulto JovemRESUMO
Most isolated congenital heart defects are thought to be sporadic and are often ascribed to multifactorial mechanisms with poorly understood genetics. Total Anomalous Pulmonary Venous Return (TAPVR) occurs in 1 in 15,000 live-born infants and occurs either in isolation or as part of a syndrome involving aberrant left-right development. Previously, we reported causative links between TAVPR and the PDGFRA gene. TAPVR has also been linked to the ANKRD1/CARP genes. However, these genes only explain a small fraction of the heritability of the condition. By examination of phased single nucleotide polymorphism genotype data from 5 distantly related TAPVR patients we identified a single 25 cM shared, Identical by Descent genomic segment on the short arm of chromosome 12 shared by 3 of the patients and their obligate-carrier parents. Whole genome sequence (WGS) analysis identified a non-synonymous variant within the shared segment in the retinol binding protein 5 (RBP5) gene. The RBP5 variant is predicted to be deleterious and is overrepresented in the TAPVR population. Gene expression and functional analysis of the zebrafish orthologue, rbp7, supports the notion that RBP5 is a TAPVR susceptibility gene. Additional sequence analysis also uncovered deleterious variants in genes associated with retinoic acid signaling, including NODAL and retinol dehydrogenase 10. These data indicate that genetic variation in the retinoic acid signaling pathway confers, in part, susceptibility to TAPVR.
Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Síndrome de Cimitarra/genética , Transdução de Sinais , Tretinoína/metabolismo , Animais , Cromossomos Humanos Par 12/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Frequência do Gene/genética , Técnicas de Silenciamento de Genes , Variação Genética , Coração/embriologia , Coração/fisiologia , Humanos , Masculino , Morfolinos/farmacologia , Linhagem , Software , Peixe-Zebra/embriologia , Peixe-Zebra/genética , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
Scimitar syndrome is a congenital anomaly occurring in approximately 1/50,000 births, consisting of partial anomalous pulmonary venous return, right lung hypoplasia, and several associated defects. The condition generally has significant morbidity and mortality, but the underlying cause is poorly understood. In this report, we describe 2 autopsy cases of Scimitar syndrome associated with multiple skeletal anomalies and attempt to characterize possible genetic abnormalities in this condition. In light of these findings, we discuss the embryology and direct timing during development of the anomalies associated with this syndrome.
Assuntos
Anormalidades Múltiplas/patologia , Pulmão/patologia , Síndrome de Cimitarra/genética , Síndrome de Cimitarra/patologia , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/genética , Diagnóstico Diferencial , Feminino , Genômica , Humanos , Lactente , Recém-Nascido , Pulmão/irrigação sanguínea , Masculino , Análise de Sequência com Séries de Oligonucleotídeos , Síndrome de Cimitarra/etiologia , Veia Cava Inferior/patologiaRESUMO
Familial recurrence of congenital heart disease (CHD), in particular, d-transposition of great arteries (d-TGA) is rare. However, there have been several reports in the literature of sibling recurrence of total anomalous pulmonary venous return (TAPVR). This is the first case report in the literature, describing mother to offspring recurrence of d-TGA. We describe two cases of non-syndromic CHD with mother to offspring and sibling recurrence. The first case is an antenatally diagnosed d-TGA on fetal echocardiogram at 25 weeks of gestational age in the offspring of a 30-year-old mother with d-TGA. The second case is a sibling reoccurrence of TAPVR diagnosed antenatally at 30 weeks of gestational age, with supradiaphragmatic TAPVR on fetal echocardiogram in a mother, whose first child was diagnosed with infradiaphragmatic TAPVR in infancy.
Assuntos
Síndrome de Cimitarra/genética , Transposição dos Grandes Vasos/genética , Adulto , Feminino , Humanos , Recém-Nascido , Masculino , Linhagem , Gravidez , Síndrome de Cimitarra/diagnóstico por imagem , Transposição dos Grandes Vasos/diagnóstico por imagem , Ultrassonografia Pré-NatalAssuntos
Anormalidades Múltiplas , Ecocardiografia , Cardiopatias Congênitas/diagnóstico por imagem , Anormalidades Múltiplas/diagnóstico por imagem , Anormalidades Múltiplas/genética , Diagnóstico Diferencial , Deformidades Congênitas da Mão/genética , Cardiopatias Congênitas/genética , Humanos , Síndrome de Cimitarra/genética , Telangiectasia Hemorrágica Hereditária/genéticaRESUMO
The authors report a new case of a familial form of the scimitar syndrome: father and son. Both presented an adult form which was well tolerated. Another familial form has been reported in the medical literature: father and daughter. The authors discuss the possible genetic mode of transmission in the light of these two cases.
Assuntos
Cardiopatias Congênitas/genética , Síndrome de Cimitarra/genética , Adulto , Criança , Ecocardiografia Doppler , Cardiopatias Congênitas/diagnóstico , Humanos , Masculino , Síndrome de Cimitarra/diagnóstico , Tomografia por Raios XRESUMO
One hundred twenty-two cases of the adult form of the scimitar syndrome were collected from different cardiologic centers. The clinical, radiographic and hemodynamic findings are described. The scimitar syndrome is defined as an anomalous right pulmonary venous drainage, partial or complete, to the inferior vena cava. Additional characteristics of this syndrome such as hypoplasia and abnormalities of the vascular supply to the right lung, dextrocardia and abnormalities of the bronchial segmentation are common; bronchiectases are rare. The left to right shunt was less than 50% in 100 of the 122 patients. The pulmonary arterial pressures were normal in 94 patients and slightly elevated in 28. A follow-up study of these patients showed that, without surgical correction, they lead a normal life. An awareness of this syndrome may avoid unnecessary invasive diagnostic procedures and surgical treatment for most patients.