Recurrence risk figures for isolated tetralogy of Fallot after screening for 22q11 microdeletion

Tissue engineering: Relevance to neonatal congenital heart disease

Congenital heart disease (CHD) represents a large clinical burden, representing the most common cause of birth defect-related death in the newborn. The mainstay of treatment for CHD remains palliative surgery using prosthetic vascular grafts and valves. These devices have limited effectiveness in pediatric patients due to thrombosis, infection, limited endothelialization, and a lack of growth potential. Tissue engineering has shown promise in providing new solutions for pediatric CHD patients through the development of tissue engineered vascular grafts, heart patches, and heart valves. In this review, we examine the current surgical treatments for congenital heart disease and the research being conducted to create tissue engineered products for these patients. While much research remains to be done before tissue engineering becomes a mainstay of clinical treatment for CHD patients, developments have been progressing rapidly towards translation of tissue engineering devices to the clinic.

The evolution of fetal echocardiography before and during COVID-19

The World Health Organization declared the novel coronavirus, or COVID-19, a pandemic in March 2020. Given the severity of COVID-19, appropriate use criteria have been implemented for fetal echocardiography. Screening low risk pregnancies for critical congenital heart disease has typically been a shared responsibility by pediatric cardiologists, obstetricians, and maternal fetal medicine (MFM). Currently, many of the fetal echocardiograms for low risk pregnancies for critical congenital heart disease have been deferred or cancelled with the emphasis on suspected abnormalities by MFMs and obstetricians. In this review, we discuss the literature that has been the basis of screening of low risk pregnancies by pediatric cardiologists. A new approach to more widespread usage of fetal tele-echocardiography may play a large part during COVID-19 and may continue after the pandemic.

•

Appropriate use criteria for fetal echocardiography have been implemented during the COVID-19 pandemic.

•

Pediatric cardiologists have deferred fetal echo for low risk pregnancies, emphasizing those with suspected abnormalities.

•

Current fetal echo guidelines highlight maternal, familial, and fetal risk factors, and the associated incidence of CHD.

•

Fetal tele-echocardiography and telehealth consultation may enhance the ability to provide care during and beyond COVID-19.

Recurrent Congenital Heart Diseases Among Neonates Born to Mothers with Congenital Heart Diseases

The frequency of newborns with congenital heart disease (CHD) is approximately 1% in the general population; however, the recurrence rate of CHD in mothers with CHD differs in ethnicity and reports. We therefore aimed to determine the prevalence of CHD among neonates born to mothers with CHD in our institute in Japan. We reviewed the medical charts of 803 neonates delivered by 529 women with CHD at the National Cerebral and Cardiovascular Center from 1982 to 2016. They included isolated ventricular septal defect (VSD,31.4%), isolated atrial septal defect (ASD, 23.3%), tetralogy of Fallot (TOF,10.6%). We defined CHD in neonates as being diagnosed within 1 month of birth. We estimated that the average rate of the CHD recurrence was 3.1%. The recurrence ratios in each maternal CHD were 8.6%, 7.1%, 6.2%, 4.8%, 3.6%, and 1.5% for PS, CoA, TOF, atrioventricular septal defect, VSD, and ASD, respectively. The rate of CHD in offsprings whose mothers have CHD was 3 times greater than that of mothers with healthy hearts. Almost half of neonates with CHD had the same phenotype as their mother in our series. Especially, PS and CoA were closely related to the type of maternal CHD.

Haploinsufficiency of vascular endothelial growth factor related signaling genes is associated with tetralogy of Fallot

Purpose

To determine disease-associated single-gene variants in conotruncal defects, particularly tetralogy of Fallot (TOF).

Methods

We analyzed for rare loss-of-function and deleterious variants in FLT4 (VEGFR3) and other genes in the vascular endothelial growth factor (VEGF) pathway, as part of a genome sequencing study involving 175 adults with TOF from a single site.

Results

We identified nine (5.1%) probands with novel FLT4 variants: seven loss-of-function, including an 8-kb deletion, and two predicted damaging. In ten other probands we found likely disruptive variants in VEGF-related genes: KDR (VEGFR2; two stopgain and two nonsynonymous variants), VEGFA, FGD5, BCAR1, IQGAP1, FOXO1, and PRDM1. Detection of VEGF-related variants (19/175, 10.9%) was associated with an increased prevalence of absent pulmonary valve (26.3% vs. 3.4%, p < 0.0001) and right aortic arch (52.6% vs. 29.1%, p = 0.029). Extracardiac anomalies were rare. In an attempt to replicate findings, we identified three loss-of-function or damaging variants in FLT4, KDR, and IQGAP1 in ten independent families with TOF.

Conclusion

Loss-of-function variants in FLT4 and KDR contribute substantially to the genetic basis of TOF. The findings support dysregulated VEGF signaling as a novel mechanism contributing to the pathogenesis of TOF.

Genetic testing in congenital heart disease: A clinical approach

Congenital heart disease (CHD) is the most common type of birth defect. Traditionally, a polygenic model defined by the interaction of multiple genes and environmental factors was hypothesized to account for different forms of CHD. It is now understood that the contribution of genetics to CHD extends beyond a single unified paradigm. For example, monogenic models and chromosomal abnormalities have been associated with various syndromic and non-syndromic forms of CHD. In such instances, genetic investigation and testing may potentially play an important role in clinical care. A family tree with a detailed phenotypic description serves as the initial screening tool to identify potentially inherited defects and to guide further genetic investigation. The selection of a genetic test is contingent upon the particular diagnostic hypothesis generated by clinical examination. Genetic investigation in CHD may carry the potential to improve prognosis by yielding valuable information with regards to personalized medical care, confidence in the clinical diagnosis, and/or targeted patient follow-up. Moreover, genetic assessment may serve as a tool to predict recurrence risk, define the pattern of inheritance within a family, and evaluate the need for further family screening. In some circumstances, prenatal or preimplantation genetic screening could identify fetuses or embryos at high risk for CHD. Although genetics may appear to constitute a highly specialized sector of cardiology, basic knowledge regarding inheritance patterns, recurrence risks, and available screening and diagnostic tools, including their strengths and limitations, could assist the treating physician in providing sound counsel.

Association of TBX20 gene polymorphism with congenital heart disease in Han Chinese neonates

As a transcription factor mainly expressed in cardiovascular system, T-box 20 (TBX20) plays an important role in embryonic cardiovascular system development and adult heart function. Previous studies have identified associations of two SNPs in the T-box DNA-binding domain of TBX20 with congenital heart disease (CHD) in two Caucasian families, but the associations of TBX20 mutations underlying the more common populations with CHD remain to be uncovered. In this study, 25 unrelated Chinese Han neonates with CHD and 25 healthy children as controls were investigated for TBX20 mutations. SNP genotyping was performed by PCR-DNA sequencing. The selected SNPs were well genotyped and SNP rs3999941 was found to be strongly associated with CHD (p = 0.007). The minor allele of rs3999941 showed a high-risk factor for CHD (OR 4.24; 95 % CI 1.41-12.71). Besides, we found a new SNP site located at the 657th nucleotide of the exon 5 of TBX20 gene which may also be associated with CHD, c.657A>C. The frequency was significantly different between two groups (p = 0.011), the minor allele of SNP c.657A>C also showed a risk factor for CHD (OR 2.56; 95 % CI 1.02-6.46). These findings suggested that the TC genotype of SNP rs3999941 and AC genotype of the new SNP c.657A>C in the TBX20 gene may be risk factors for CHD and thus screening of these SNPs may have some implications in the prevention and treatment of CHD in Han Chinese children.

Reproductive Fitness and Genetic Transmission of Tetralogy of Fallot in the Molecular Age

Background—

Individuals with tetralogy of Fallot (TOF) now routinely survive to reproductive age and beyond. Reproductive fitness of adults with TOF and recurrence risks to offspring are of increasing interest in the modern era, especially given recent molecular genetic discoveries.

Methods and Results—

After excluding individuals with known genetic syndromes, 543 unrelated adults with TOF underwent a detailed family history assessment and molecular characterization for rare copy number variations using high-resolution genome-wide microarrays. Men and women with TOF had significantly fewer offspring compared with an age-matched comparison group without congenital heart disease (CHD; P =0.0004). No aspect of rare copy number variation burden was a predictor of decreased reproductive fitness. Corresponding with the advent of modern surgical repairs, reproductive fitness of women began to exceed that of men ( P =0.0490). Recurrence risk for CHD in offspring was 4.8%, with no significant differences between men and women with TOF. The risk of severe CHD in offspring (2.3%) far exceeded population expectations (relative risk, 15.6; 95% confidence interval, 7.9–31.0). Most cases of vertical transmission of CHD were not explained by the transmission of a large rare copy number variation. Although conotruncal lesions (31.5%) were the most commonly reported CHD in relatives, the familial spectrum of disease included many anatomically discordant lesions.

Conclusions—

Men and women with TOF have reduced reproductive fitness. Their offspring are at significantly elevated risk for severe CHD. These results support the importance of genetic counseling for both men and women with complex CHD. Many inherited genetic variants remain to be discovered.

Risk of congenital heart disease in relatives of probands with conotruncal cardiac defects: an evaluation of 1,620 families

Current recurrence risk counseling for conotruncal cardiac defects (CTD) is based on empiric estimates from multiple studies. We examined the risk of congenital heart disease (CHD) in relatives of probands with CTDs to assist in counseling practices in the current era. One thousand six-twenty probands with CTDs and no reported chromosomal or genetic abnormalities were recruited sequentially. A three-generation pedigree was obtained for each proband by a genetic counselor detailing the presence and type of CHD in each family member. Risks and 95% confidence intervals (CI) were calculated for sub-groups of relatives based on degree of relationship for all probands and by individual lesion of the proband. For pairs of affected relatives, concordance rates were calculated. Severity of CHD in the affected relative was assessed. The risk of CHD was higher in siblings (4.4%, 95% CI 3.4-5.4) than in parents (1.5%, 95% CI 1.1-1.9). Risk varied by the cardiac lesion of the proband with the highest risk in first-degree relatives of probands with tetralogy of Fallot and the lowest in D-transposition of the great arteries. 39% of affected parents and 69% of affected siblings had a concordant lesion (i.e., CTD). Most affected siblings of probands with severe CTDs had complex defects (58%), whereas very few affected parents had complex defects (20%). These data suggest that recurrence risk varies by lesion and relationship, with substantial concordance observed by cardiac lesion and complexity of disease, particularly among siblings. These findings contribute to risk counseling in the current era.

Repair and follow-up of Tetralogy of Fallot with pulmonary stenosis

Tetralogy of Fallot is the most common cyanotic congenital heart defect. Advances in surgical technique and postoperative care have improved survival which is now very good. Patients now face long-term morbidities such as reduced exercise tolerance and arrthymias. Cardiologists caring for these patients are confronted with decisions regarding best care practices. This article will review the evidence available on repair and postoperative follow-up for patients with Tetralogy of Fallot with pulmonary stenosis.

Design and rationale of a genetic cohort study on congenital cardiac disease: experiences from a multi-institutional platform in Quebec

BACKGROUND

Congenital cardiac disease is the most common malformation, and a substantial source of mortality and morbidity in children and young adults. A role for genetic factors is recognised for these malformations, but overall few predisposing loci have been identified. Here we report the rationale, design, and first results of a multi-institutional congenital cardiac disease cohort, assembled mainly from the French-Canadian population of the province of Quebec and centred on families with multiple affected members afflicted by cardiac malformations.

METHODS

Families were recruited into the study, phenotyped and sampled for DNA in cardiology clinics over the first 3 years of enrolment. We performed segregation analysis and linkage simulations in the subgroup of families with left ventricular outflow tract obstruction (LVOTO).

RESULTS

A total of 1603 participants from 300 families were recruited, with 169 out of 300 (56.3%) families having more than one affected member. For the LVOTO group, we estimate heritability to be 0.46-0.52 in our cohort. Simulation analysis demonstrated sufficient power to carry out linkage analyses, with an expected mean log-of-odds (LOD) score of 3.8 in 67 pedigrees with LVOTO.

CONCLUSION

We show feasibility and usefulness of a population-based biobank for genetic investigations into the causes of congenital cardiac disease. Heritability of LVOTO is high and could be accounted for by multiple loci. This platform is ideally suited for multiple analysis approaches, including linkage analysis and novel gene sequencing approaches, and will allow to establish segregation of risk alleles at family and population levels.

Complex congenital heart disease in unaffected relatives of adults with 22q11.2 deletion syndrome

The 22.q11.2 deletion syndrome (22q11DS) is a common genetic condition associated with 22q11.2 microdeletions and classically has included congenital heart disease (CHD) as a part of the variable expression. Some evidence has shown that relatives of those with 22q11DS might be at an increased risk of CHD in the absence of 22q11.2 deletions. We obtained a detailed family history of CHD in the first- to third-degree relatives (n = 2,639) of 104 adult probands with 22q11DS. We compared the prevalence of CHD in the relatives without 22q11.2 deletions to the published general population prevalence. We also investigated the effect of CHD in the probands on prevalence of CHD in the relatives. Of the 104 probands with 22q11DS, 14 (13.5%) had 17 relatives (17 of 2,639, 0.6%) with CHD. Of 66 probands with CHD, 15 (0.9%) of their 1,663 relatives had CHD, a significantly greater prevalence than that for the relatives of probands without CHD (0.2%, 2 of 976, p = 0.041, odds ratio 4.43, 95% confidence interval 1.03 to 40.00). In relatives of probands with CHD, the prevalence of those with severe CHD (0.36%) was significantly elevated compared to population expectations (0.061%, p = 0.007, odds ratio 5.88, 95% confidence interval 2.16 to 12.85). In conclusion, these results support a heritable susceptibility to CHD in families of probands with 22q11DS, in addition to that imparted by microdeletion 22q11.2. The occurrence of CHD in relatives might be related to the expression of CHD in the proband with 22q11DS. These findings have potential implications for the genetic counseling of families of those with 22q11DS and support the notion that interacting genetic variants might contribute to the variable expression of 22q11DS.

Genetic factors in non-syndromic congenital heart malformations

The genetic defect in most patients with non-syndromic congenital heart malformations (CHM) is unknown, although more than 40 different genes have already been implicated. Only a minority of CHM seems to be due to monogenetic mutations, and the majority occurs sporadically. The multifactorial inheritance hypothesis of common diseases suggesting that the cumulative effect of multiple genetic and environmental risk factors leads to disease, might also apply for CHM. We review here the monogenic disease genes with high-penetrance mutations, susceptibility genes with reduced-penetrance mutations, and somatic mutations implicated in non-syndromic CHM.

Increased prevalence of cardiovascular defects among 56,709 California twin pairs

This study compared the prevalence of cardiovascular defects in twin and singleton births and explored the influences of zygosity (monozygotic and dizygotic) and maternal age (<35 and >or=35 years of age) on concordance. Data on twin and singleton infants with (n = 628 twin pairs and n = 14,078 singletons) and without (n = 53,974 twin pairs and n = 4,858,255 singletons) cardiovascular defects were obtained from the California Birth Defects Monitoring Program and the California vital statistics birth and fetal death records during the period 1983-2003. Prevalence ratios (PR) (prevalence of twin/singleton) and approximate 95% confidence intervals were calculated for 16 congenital cardiovascular categories. Poisson regression techniques using log-linear models were employed to assess whether the probability of concordance of defects within each cardiovascular category varied by zygosity or maternal age. An increased prevalence was observed in twins compared to singletons in all 16 cardiovascular categories. Seven of the cardiovascular categories had at least double the prevalence in twins compared to singletons. Like-sex twins, as a proxy of monozygosity, had an increased prevalence of cardiovascular defects compared to unlike sex twins. Probabilities of concordance for flow lesions were higher among monozygotic than dizygotic twins. Our study provides evidence that twinning is associated with more cardiovascular defects than singletons. Increased concordance for flow lesions in monozygotic twins was observed, an observation that is in agreement with findings from familial recurrence studies of cardiovascular defects.

Congenital heart disease and genetics

Improvements in the diagnosis and treatment of congenital heart disease have drastically reduced the morbidity and mortality associated with such defects. Knowledge regarding the genetic contributions to congenital heart disease is considered to be in its infancy; however, the field of cardiovascular genetics in humans is moving at a rapid pace. This article discusses what is currently known about the genetic contribution to congenital heart disease, including structural defects and congenital cardiac arrhythmias. Genetic and chromosomal syndromes that involve the heart are reviewed along with genetic testing.

Congenital cardiac disease and inbreeding: specific defects escape higher risk due to parental consanguinity

AIMS

To test on a large cohort whether parental consanguinity varies among different types of congenitally malformed hearts.

METHODS AND RESULTS

Between 1 May, 1999, and 28 February, 2006, a large cohort of 1585 newly diagnosed cases with non-syndromic congenitally malformed heart was enrolled at the National Register of Paediatric and Congenital Heart Disease, Lebanese Society of Cardiology, Beirut. Another group, made up of 1979 cases referred to the National Register of Paediatric and Congenital Heart Disease, but free of any malformation, and with a rate of consanguinity similar to a recent survey made by UNICEF in Lebanon, was used for the purposes of control. We used the Chi-squared test, and ratio of risk, to compare the groups. Subgroups with first degree cousins, first plus second degree cousins, and any degree of consanguinity, are significantly larger in the cohort with congenitally malformed hearts than in the control cohort, with proportions of 19.4%, 25.7%, and 27.4% versus 14.4%, 20.3%, and 23.9%, respectively. Those with tetralogy of Fallot, valvar aortic stenosis, and atrial septal defect have a significantly higher percentage of consanguineous parents than do the controls. By contrast, this is not the case for those with atrioventricular septal defect and common atrioventricular junction ("atrioventricular canal"), or discordant ventriculo-arterial connections ("transposition"). These differences persist when the types of congenital cardiac defect types are pooled according to presumed embryological processes. Those with hypoplasia of the left heart have increased parental consanguinity, but not the group of various types of discordant ventriculo-arterial connections.

CONCLUSION

Only some types of congenitally malformed hearts have an increased percentage of parental consanguinity, suggesting that those types with no increased risk due to parental consanguinity are determined by genetic factors that are X-linked or exclusively autosomal dominant.

Deletion 22q11 and isolated congenital heart disease

The real prevalence of deletion 22 (del22) in isolated congenital heart defects is still disputed. The experience of our group suggests that patients with CHD and del22 have classic or subtle extracardiac features, so that an accurate clinical evaluation of patients with CHD is needed before stating that the defect is isolated.

Familial recurrence of congenital heart disease: an overview and review of the literature

Familial recurrence is one of the classic patterns for the clinical presentation of congenital heart disease (CHD). In recent years, many groups studied empiric recurrence risk in these heart defects, and the aim of this review was to analyse the patterns of inheritance detected in different types of CHD, including atrioventricular canal defect, tetralogy of Fallot, transposition of the great arteries, left-sided obstructions and atrial septal defect. These studies may influence clinical practise guidelines through accurate genetic counselling, but also, they may have important implications in the knowledge of genetic and pathogenetic mechanisms of CHD.

Familial recurrence of nonsyndromic congenital heart defects in first degree relatives of patients with deletion 22q11.2

The majority of nonsyndromic congenital heart defects (CHDs) are considered to follow a multifactorial model of inheritance. Multiple family members affected by CHD can occasionally be detected, and the involvement of several genetic loci interacting with environmental factors is suspected to be implicated. The DiGeorge/velo-cardio-facial syndrome related to microdeletion 22q11.2 (del22) is a genetic condition associated with CHD in most of the cases. We report here on five pedigrees of patients with del22, showing occurrence of nonsyndromic CHD in a first-degree relative of the proband case. Familial aggregation of syndromic and nonsyndromic CHD as observed in our series is to be considered as an unusual pattern of recurrence. The interaction between several different genes and environmental factors, a familial susceptibility predisposing to a specific cardiac malformation, or chance association can all be hypothesized searching an explanation for these particular observations.

Mutations of ZFPM2/FOG2 gene in sporadic cases of tetralogy of Fallot

Two out of 47 patients with sporadic tetralogy of Fallot (TOF), the most common cyanotic conotruncal heart defect (CTD), showed heterozygous missense mutations of the ZFPM2/FOG2 gene. Knockout mice carrying mutations in the ZFPM2/FOG2 gene have similarly been found to exhibit TOF. While both mutant ZFPM2/FOG2 proteins, E30G (c.88A>G) and S657G (c.1968A>G), retain the ability to bind the partner protein GATA4 and repress GATA4 mediated gene activation, the S657G, but not the E30G, mutation is subtly impaired in this function. ZFPM2/FOG2 gene mutations may contribute to some sporadic cases of TOF.

DiGeorge subtypes of nonsyndromic conotruncal defects: evidence against a major role of TBX1 gene

The role of the 22q11 region genes, and among them TBX1, in nonsyndromic conotruncal defects (CTDs) is still unclear. Mice hemizygous at the Tbx1 locus show a remarkable incidence of heart outflow tract anomalies, of the same type commonly found in DiGeorge/Velo-cardio-facial syndrome (DGS/VCFS). Mutation analysis of the TBX1 gene in isolated, nonsyndromic CTDs has not demonstrated any functional pathogenetic variation so far. We screened the TBX1 gene in 41 patients affected by nonsyndromic CTDs of the DGS/VCFS subtype, principally "atypical" tetralogy of Fallot. Besides a few polymorphisms, we did not find any pathogenetic variation. These results do not support a major role of the TBX1 gene as responsible for human nonsyndromic CTDs.

22q11.2 microdeletions in adults with familial tetralogy of Fallot

PURPOSE

To determine the incidence of 22q11.2 microdeletions in the adult survivors of correction of tetralogy of Fallot who have familial congenital heart disease.

METHODS

Patients who had survived a correction of tetralogy of Fallot between 1954 and 1974 and had affected family members were identified during a study of these long-term survivors. Fluorescence in situ hybridization analysis was performed using both the N 25 (Oncor) and TUPLE1(VYSIS) probes, mapped to 22q11.2.

RESULTS

One of 18 (5.6%) patients had a microdeletion within 22q11.2, including both N25 and TUPLE1.

CONCLUSION

22q11.2 microdeletions involving TUPLE1 and/or N25 are present in a minority of adults with familial tetralogy of Fallot.

Familial recurrence of nonsyndromic interrupted aortic arch and truncus arteriosus with atrioventricular canal

BACKGROUND

Multifactorial inheritance is probably involved in most cases of nonsyndromic conotruncal heart defects (CHDs), but Mendelian transmission is often suspected.

RESULTS

We report on a family with recurrence of nonsyndromic CTHD in two double first cousins; i.e., two brothers married two sisters. One of the cousins (case 1) had interrupted aortic arch (IAA) type B, while the other one (case 2) had truncus arteriosus (TA) with atrioventricular canal defect (AVCD).

CONCLUSIONS

Our family further supports monogenic inheritance of CTHDs. In addition, the presence of TA associated with AVCD in one of the patients confirms the higher occurrence of CTHD in families with complex TA. The absence of 22q11 microdeletion (del22q11) in our patients, as in several literature reports of familial CTHDs, supports the existence of genes different to those located on chromosome 22q11 which could be implicated in the pathogenesis of CTHDs.

Congenital heart defect in sibs with discordant karyotypes

Congenital heart defects (CHDs) are genetically heterogeneous, associated with a variety of genetic conditions. Familial aggregation of CHD in patients with and without Down syndrome is rare. We report on the occurrence of concordant CHD in three sets of sibs with discordant karyotypes. In the first family, atrioventricular canal (AVC) was diagnosed in a chromosomally normal child and in his brother with Down syndrome. In the second family, AVC was associated with trisomy 21 in one sib and with trisomy 18 in the other. In the third family, tetralogy of Fallot was present in one patient with Down syndrome and in his nonsyndromic sister. Although the genetic heterogeneity of Down and non-Down CHD is not disputed, a susceptibility to both euploid and aneuploid CHDs could exist, and common predisposing factors could play a role in both conditions.

Conotruncal heart defect/microphthalmia syndrome: delineation of an autosomal recessive syndrome

We report on three sibs born to healthy parents, one livebirth and two terminated pregnancies, presenting with a malformation complex characterised by conotruncal heart defect (CTHD), microphthalmia, genital anomalies, and facial dysmorphism. The recurrence of the association of CTHD, particularly truncus arteriosus, and microphthalmia in sibs has previously been reported in rare instances, but a correlation between the single descriptions has never been noted. CTHDs are included among the cardiac malformations characteristically associated with the group of syndromes caused by the microdeletion of chromosome 22q11, but no detectable hemizygosity has been found in our family. An autosomal recessive gene seems to be involved in syndromic patients with the combination of CTHD and microphthalmia. The map location of this gene is at present unknown, but autosomal recessive inheritance must be considered in genetic counselling of families with children presenting with this malformation complex.