Elizabeth Goldmuntz

Variants of folate metabolism genes and the risk of conotruncal cardiac defects.

Background—Although congenital heart defects (CHD) are the most common and serious group of birth defects, relatively little is known about the causes of these conditions and there are no established prevention strategies. There is evidence suggesting that the risk of CHD in general, and conotruncal and ventricular septal defects in particular, may be related to maternal folate status as well as genetic variants in folate-related genes. However, efforts to establish the relationships between these factors and CHD risk have been hampered by a number of factors including small study sample sizes and phenotypic heterogeneity. Methods and Results—The present study examined the relationships between variation in 9 folate-related genes and a subset of CHD phenotypes (ie, conotruncal defects, perimembranous and malalignment type ventricular septal defects, and isolated aortic arch anomalies) in a cohort of >700 case-parent triads. Further, both maternal and embryonic genetic effects were considered. Analyses of the study data confirmed an earlier reported association between embryonic genotype for MTHFR A1298C and disease risk (unadjusted P=0.002). Conclusions—These results represent the most comprehensive and powerful analysis of the relationship between CHD and folate-related genes reported to date, and provide additional evidence that, similar to neural tube defects, this subset of CHD is folate related.

Jagged1 (JAG1) mutations in patients with tetralogy of Fallot or pulmonic stenosis.

Mutations in the Notch pathway ligand Jagged1 (JAG1) cause Alagille syndrome (AGS), as well as cardiac defects in seemingly nonsyndromic individuals. To estimate the frequency of JAG1 mutations in cases with right‐sided cardiac defects not otherwise diagnosed with AGS, we screened 94 cases with tetralogy of Fallot (TOF) and 50 with pulmonic stenosis/peripheral pulmonary stenosis (PS/PPS) or pulmonary valve atresia with intact ventricular septum (PA) for mutations. Sequence changes were identified in three TOF and three PS/PPS/PA patients, that were not present in 100 controls. We identified one frameshift and two missense mutations in the TOF cases, and one frameshift and two missense mutations in cases with PS/PPS/PA. The four missense mutations were assayed for their effect on protein localization, posttranslational modification, and ability to activate Notch signaling. The missense mutants displayed heterogeneous behavior in these assays, some with complete haploinsufficiency, suggesting that there are additional modifiers leading to organ specific features. We identified functionally significant mutations in 2% (2/94) of TOF patients and 4% (2/50) of PS/PPS/PA patients. Patients with right‐sided cardiac defects should be carefully screened for features of AGS or a family history of cardiac defects that might suggest the presence of a JAG1 mutation. Hum Mutat 31:594–601, 2010.

Low expression VEGF haplotype increases the risk for tetralogy of Fallot: a family based association study

Congenital heart disease (CHD) presents a huge medical problem, as it affects between two and eight newborn children per 100 live births.1 Risk factors include alcohol and drug consumption as well as genetic defects. However, chromosomal and single gene defects cause only a relatively minor proportion of cases and, thus, most CHD is considered to be multi-factorial in origin, with various genes interacting with each other or with environmental factors to determine disease liability.2 To date, none of the CHD genetic susceptibility factors have been discovered.nnTetralogy of Fallot (TOF) is a common form of CHD, characterised by a subaortic ventricular septum defect (VSD), an overriding aorta, a right ventricular outflow tract obstruction, and right ventricular hypertrophy. TOF occurs in 4.21 of every 10 000 births and is the most common type of CHD with cyanosis after 1 year of life.1 TOF may occur as part of the DiGeorge syndrome (DGS) which is caused by deletions of chromosome 22q11 and characterised by conotruncal cardiac, craniofacial, thymic, and parathyroid anomalies. However, in most cases (in 2.65 per 10 000 children) TOF occurs as an isolated defect. Mutations in the JAGGED1 or NKX2.5 genes have been found in only a few percentages of cases with isolated, non-syndromic TOF and thus, the genetic etiology in the large majority of these cases remains entirely unknown.2 By using a multi-genetic approach, we recently discovered that VEGF is a modifier of DGS.3 We therefore assessed here whether VEGF might be a modifier of the cardiac birth defects in subjects with isolated, non-syndromic TOF.nn### Study design and participantsnnTo examine whether VEGF gene variations are associated with TOF, we used the transmission disequilibrium test (TDT) to analyse linkage disequilibrium of single nucleotide polymorphisms (SNPs) in the VEGF gene in trios of parents and their proband affected …

Late effects in survivors of tandem peripheral blood stem cell transplant for high-risk neuroblastoma.

Increasing numbers of children with advanced neuroblastoma are achieving cure. We describe the clinical late effects specific to survivors of stage IV neuroblastoma all similarly treated using tandem autologous peripheral blood stem cell rescue with TBI.

The 22q11.2 Deletion in African-American Patients: An Underdiagnosed Population?

Findings associated with the 22q11.2 deletion often include congenital heart malformations, palatal anomalies, immunodeficiency, hypocalcemia, and developmental delay or learning disabilities. Often the clinical suspicion of the diagnosis in a patient with one or more of these findings is heightened based on the presence of a characteristic facial appearance. In our large cohort of 370 patients with the 22q11.2 deletion, we report the under‐representation of African‐Americans in our group, as well as, the paucity of craniofacial dysmorphism in these patients. We note that the absence of the typical facial features may result in decreased ascertainment in this population and, furthermore, may delay the implementation of palliative care, cognitive remediation, and recurrence risk counseling. We, therefore, suggest that the clinicians threshold of suspicion should be lower in African‐American patients.

Gene-Gene Interactions in the Folate Metabolic Pathway and the Risk of Conotruncal Heart Defects

Conotruncal and related heart defects (CTRD) are common, complex malformations. Although there are few established risk factors, there is evidence that genetic variation in the folate metabolic pathway influences CTRD risk. This study was undertaken to assess the association between inherited (i.e., case) and maternal gene-gene interactions in this pathway and the risk of CTRD. Case-parent triads (n = 727), ascertained from the Childrens Hospital of Philadelphia, were genotyped for ten functional variants of nine folate metabolic genes. Analyses of inherited genotypes were consistent with the previously reported association between MTHFR A1298C and CTRD (adjusted P = .02), but provided no evidence that CTRD was associated with inherited gene-gene interactions. Analyses of the maternal genotypes provided evidence of a MTHFR C677T/CBS 844ins68 interaction and CTRD risk (unadjusted P = .02). This association is consistent with the effects of this genotype combination on folate-homocysteine biochemistry but remains to be confirmed in independent study populations.

Evaluation of potential modifiers of the cardiac phenotype in the 22q11.2 deletion syndrome.

BACKGROUNDnThe phenotype associated with deletion of the 22q11.2 chromosomal region is highly variable, yet little is known about the source of this variability. Cardiovascular anomalies, including tetralogy of Fallot, truncus arteriosus, interrupted aortic arch type B, perimembranous ventricular septal defects, and aortic arch anomalies, occur in approximately 75% of individuals with a 22q11.2 deletion.nnnMETHODSnData from 343 subjects enrolled in a study of the 22q11.2 deletion syndrome were used to evaluate potential modifiers of the cardiac phenotype in this disorder. Subjects with and without cardiac malformations, and subjects with and without aortic arch anomalies were compared with respect to sex and race. In addition, in the subset of subjects from whom a DNA sample was available, genotypes for variants of four genes that are involved in the folate-homocysteine metabolic pathway and that have been implicated as risk factors for other birth defects were compared. Five variants in four genes were genotyped by heteroduplex or restriction digest assays. The chi-square or Fishers exact test was used to evaluate the association between the cardiac phenotype and each potential modifier.nnnRESULTSnThe cardiac phenotype observed in individuals with a 22q11.2 deletion was not significantly associated with either sex or race. The genetic variants that were evaluated also did not appear to be associated with the cardiovascular phenotype.nnnCONCLUSIONSnVariation in the cardiac phenotype observed between individuals with a 22q11.2 deletion does not appear to be related to sex, race, or five sequence variants in four folate-related genes that are located outside of the 22q11.2 region.

Serum alkaline phosphatase reflects post-Fontan hemodynamics in children.

Although survivors of Fontan palliation for a single ventricle are known to have lower cardiac index than patients with two-ventricle surgical reconstructions, it is unclear whether two frequently observed sequelae, short stature and protein-losing enteropathy (PLE), have hemodynamic origins. A serum marker that reflects hemodynamic status would be a tremendous asset in the long-term management of children with these sequelae. The authors recently noted severely reduced total alkaline phosphatase (TALP) levels in two children with early-onset PLE after Fontan operations, both of whom had low cardiac output at cardiac catheterization. Catheter-based or surgical interventions that rapidly increased cardiac output in these two patients resulted not only in relief of PLE but also in a prompt TALP rise. To examine whether the apparent correlation of low TALP with impaired cardiac output also is seen in Fontan patients without PLE, this study retrospectively examined the TALP data from two other Fontan patients who underwent cardiac catheterization specifically to assess the potential benefit of vasodilator therapy. The TALP levels were abnormally low in both cases but increased after uptitration of angiotensin-converting enzyme inhibition. Serum TALP activity, an indicator of osteoblastic function particularly in preadolescence, may be a marker of low cardiac output after a Fontan operation.

Mutational analysis of the PITX2 coding region revealed no common cause for transposition of the great arteries (dTGA)

BackgroundPITX2 is a bicoid-related homeodomain transcription factor that plays an important role in asymmetric cardiogenesis. Loss of function experiments in mice cause severe heart malformations, including transposition of the great arteries (TGA). TGA accounts for 5–7% of all congenital heart diseases affecting 0.2 per 1000 live births, thereby representing the most frequent cyanotic heart defect diagnosed in the neonatal period.MethodsTo address whether altered PITX2 function could also contribute to the formation of dTGA in humans, we screened 96 patients with dTGA by means of dHPLC and direct sequencing for mutations within the PITX2 gene.ResultsSeveral SNPs could be detected, but no stop or frame shift mutation. In particular, we found seven intronic and UTR variants, two silent mutations and two polymorphisms within the coding region.ConclusionAs most sequence variants were also found in controls we conclude that mutations in PITX2 are not a common cause of dTGA.

Partial Anomalous Left Pulmonary Artery

A 4-year-old girl with Kabuki syndrome was evaluated and diagnosed with an atrial septal defect on the basis of an abnormal cardiac physical examination. A chest radiograph was performed, which demonstrated multiple skeletal abnormalities and mild prominence of the pulmonary vasculature consistent with an atrial septal defect (Figure 1). A complete echocardiogram was performed under sedation, which demonstrated the atrial septal defect as well as dual pulmonary arterial supply to the left lung with a partial anomalous left pulmonary artery (LPA) from the right pulmonary artery (RPA) (Figure 2). Cardiac magnetic resonance (MR) imaging was performed to further delineate pulmonary arterial anatomy as well as possible tracheal compression from the partial anomalous LPA. nnnnFigure 1. Chest radiograph in the anteroposterior projection demonstrates irregularity of the right clavicle with separation of the hypoplastic distal half (arrowhead), butterfly vertebrae of T11 (arrow), absence of the left twelfth rib (asterisk), mild prominence of the pulmonary vasculature, and a normal cardiac silhouette.nnnnnnFigure 2. High parasternal short-axis echocardiogram with color compare shows the partial anomalous LPA (ALPA) arising from the RPA. AAo indicates ascending aorta; MPA, main pulmonary artery; and DRPA, distal RPA.nnnnA complete cardiac MR study was performed including gadolinium-enhanced MR angiography. The 3-dimensional reconstructed MR angiography data set demonstrates that the left lung receives blood supply from 2 left pulmonary arteries. One of …