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Aims Holt–Oram syndrome (HOS) is a heart/hand syndrome clinically characterized by upper limb and cardiac malformations. Mutations in T-box transcription factor 5 ( TBX5 ) underlie this syndrome, the majority of which lead to premature stops. In this study, we present our functional analyses of five (novel) missense TBX5 mutations identified in HOS patients, most of whom presented with severe cardiac malformations. Methods and results Functional characterization of mutant proteins shows a dramatic loss of DNA-binding capacity, as well as diminished binding to known cardiac interaction partners NKX2-5 and GATA4. The disturbance of these interactions leads to a loss of function, as measured by the reduced activation of Nppa and FGF10 in rat heart derived cells, although with variable severity. Two out of the five mutations are peculiar: one, p.H220del, is associated with additional extra-cardiac defects, perhaps by interfering with other T-box dependant pathways, and another, p.I106V, leads to limb defects only, which is supported by its normal interaction with cardiac-specific interaction partners. Conclusion Overall, our data are consistent with the hypothesis that these novel missense mutations in TBX5 lead to functional haploinsufficiency and result in a reduced transcriptional activation of target genes, which is likely central to the pathogenesis of HOS.

Background Three quarters of patients with 22q11.2 Deletion Syndrome (22q11.2DS) have congenital heart disease (CHD), typically conotruncal heart defects. Although it is currently common practice to test all children with typical CHD for 22q11.2DS, many adult patients have not been tested in the past and therefore 22q11.2DS might be under-recognised in adults. Objectives To determine the prevalence of 22q11.2DS in adults with tetralogy of Fallot (TOF) and pulmonary atresia (PA)/ventricular septal defect (VSD) and to assess the level of recognition of the syndrome in adult patients. Methods Patients were identified from CONCOR, a nationwide registry for adult patients with CHD. Inclusion criteria were diagnosis of TOF or PA/VSD and the availability of DNA. Patients with syndromes other than 22q11.2DS were excluded. Multiplex ligation-dependent probe amplification was used to detect 22q11.2 microdeletions. Results 479 patients with TOF and 79 patients with PA/VSD (56% male, median age 34.7 years) were included and analysed. Twenty patients were already known to have 22q11.2DS. A 22q11.2 microdeletion was detected in a further 24 patients. Thirty-one patients with TOF (6.5%) had 22q11.2DS, whereas 13 patients with PA/VSD had 22q11.2DS (16.5%). Of all 22q11.2 microdeletions, 54% (24/44) were unknown before this study. Conclusion This study shows that although the prevalence of 22q11.2DS in adults with TOF and PA/VSD is substantial, it is unrecognised in more than half of patients. As the syndrome has important clinical and reproductive implications, a diagnostic test should be considered in all adult patients with TOF and PA/VSD.

Background— Catecholaminergic polymorphic ventricular tachycardia is a disease characterized by ventricular arrhythmias elicited exclusively under adrenergic stress. Additional features include baseline bradycardia and, in some patients, right ventricular fatty displacement. The clinical spectrum is expanded by the 2 families described here. Methods and Results— Sixteen members from 2 separate families have been clinically evaluated and followed over the last 15 years. In addition to exercise-related ventricular arrhythmias, they showed abnormalities in sinoatrial node function, as well as atrioventricular nodal function, atrial fibrillation, and atrial standstill. Left ventricular dysfunction and dilatation was present in several affected individuals. Linkage analysis mapped the disease phenotype to a 4-cM region on chromosome 1q42-q43. Conventional polymerase chain reaction–based screening did not reveal a mutation in either the Ryanodine receptor 2 gene ( RYR2 ) or ACTN2 , the most plausible candidate genes in the region of interest. Multiplex ligation-dependent probe amplification and long-range polymerase chain reaction identified a genomic deletion that involved RYR2 exon-3, segregated in all the affected family members (n=16) in these 2 unlinked families. Further investigation revealed that the genomic deletion occurred in both families as a result of Alu repeat–mediated polymerase slippage. Conclusions— This is the first report on a large genomic deletion in RYR2 , which leads to extended clinical phenotypes (eg, sinoatrial node and atrioventricular node dysfunction, atrial fibrillation, atrial standstill, and dilated cardiomyopathy). These features have not previously been linked to RYR2 .

Introduction: Previously, autosomal dominant catecholaminergic polymorphic ventricular tachycardia (CPVT [1]) was mapped to chromosome 1q42–43 with identification of pathogenic mutations in RYR2. Autosomal recessive CPVT (2) was mapped to chromosome 1p13–21, leading to the identification of mutations in CASQ2. In this study, we aimed to elucidate clinical phenotypes of a new variant of CPVT (3) in an inbred Arab family and also delineate the chromosomal location of the gene causing CPVT (3). Methods and Results: In a highly inbred family, clinical symptoms of CPVT appeared early in childhood (7–12 years) and in three of the four cases, the first appearance of symptoms turned into a fatal outcome. Parents of the affected children were first-degree cousins and without any symptoms. Segregation analysis suggested an autosomal recessive inheritance. A genome-wide search using polymorphic DNA markers mapped the disease locus to a 25-Mb interval on chromosome 7p14-p22. A maximal multipoint LOD score of 3.17 was obtained at marker D7S493. Sequencing of putative candidate genes, SP4, NPY, FKBP9, FKBP14, PDE1C, and TBX20, in and around this locus, did not reveal any mutation. Conclusions: We have identified a novel highly malignant autosomal recessive form of CPVT and mapped this disorder to a 25-Mb interval on chromosome 7p14-p22.

Establishing correct left-right asymmetry during embryonic development is crucial for proper asymmetric positioning of the organs. Congenital heart defects, such as dextrocardia, transposition of the arteries, and inflow or outflow tract malformations, comprise some of the most common birth defects and may be attributed to incorrect establishment of body laterality. Here, we identify new patients with dextrocardia who have mutations in CFAP53, a coiled-coil domain containing protein. To elucidate the mechanism by which CFAP53 regulates embryonic asymmetry, we used genome editing to generate cfap53 zebrafish mutants. Zebrafish cfap53 mutants have specific defects in organ laterality and randomization of asymmetric gene expression. We show that cfap53 is required for cilia rotation specifically in Kupffer's vesicle, the zebrafish laterality organ, providing a mechanism by which patients with CFAP53 mutations develop dextrocardia and heterotaxy, and confirming previous evidence that left-right asymmetry in humans is regulated through cilia-driven fluid flow in a laterality organ.

Wereldwijd zijn kinderoncologen van mening dat de follow-up van overlevenden van jeugdkanker levenslang voortgezet dient te worden. Op de vraag waar en door wie deze controles moeten worden uitgevoerd zijn verschillende antwoorden mogelijk. Het doel van de follow-up is tweeledig: patientenzorg en registratie van de late effecten ten behoeve van wetenschappelijk onderzoek. Maar dit zijn geen gescheiden entiteiten, want het wetenschappelijk onderzoek is noodzakelijk voor goede evidence-based patientenzorg. Het verdient aanbeveling om de verschillende modellen van zorg op hun effectiviteit en doelmatigheid te onderzoeken alvorens voor een bepaalde werkwijze te kiezen.langetermijneffecten kinderkanker, overlevenden van follow-up, langdurige

Background: The aim of the study was to assess underlying genetic cause(s), clinical features, and response to therapy in catecholaminergic polymorphic ventricular tachycardia (CPVT) probands. Methods and results: We identified 13 missense mutations in the cardiac ryanodine receptor (RYR2) in 12 probands with CPVT. Twelve were new, of which two are de novo mutations. A further 11 patients were silent gene carriers, suggesting that some mutations are associated with low penetrance. A marked resting sinus bradycardia off drugs was observed in all carriers. On beta blocker treatment, 98% of the RYR2 mutation carriers remained symptom free with a median follow up of 2 (range: 2-37) years. Conclusion: CPVT patients with RYR2 mutation have bradycardia regardless of the site of the mutation, which could direct molecular diagnosis in (young) patients without structural heart disease presenting with syncopal events and a slow heart rate but with normal QTc at resting ECG. Treatment with b blockers has been very effective in our CPVT patients during initial or short term follow up. Given the risk of sudden death and the efficacy of b blocker therapy, the identification of large numbers of RYR2 mutations thus calls for genetic screening, early diagnosis, and subsequent preventive strategies

Congenital heart disease (CHD) is the most common type of birth defect, accounting for one-third of all major congenital anomalies, identifiable in up to 10% of stillbirths and presumed to play a major role in early fetal demise. Worldwide, 1.35 million infants are born with CHD each year [1]. CHDs range from milder forms such as bicuspid aortic valves through conotruncal cardiac defects associated with severe late complications, requiring lifelong medical care [2]. The advent of corrective cardiac surgery and the increase in knowledge concerning the longitudinal care of CHD patients have led to a spectacular increase in life expectancy. Nowadays, 490% of children with CHD will live into adulthood [3]. Epidemiological studies suggest that CHD arises primarily through genetic abnormalities. However, with the exception of long-recognized chromosomal abnormalities (e.g., trisomy 21) and point mutations in a limited set of developmental genes (e.g., NKX2-5, GATA4, and NOTCH1), genetic factors underlying CHD have remained elusive [1]. Classical genetic methodologies were until recently restricted to gene discovery efforts of familial forms of CHD with highly penetrant inheritance. These have, with some exceptions, been largely unsuccessful due to the lack of large families with multiple affected individuals (rare in CHD). With the availability of only small families, or the absence of familial aggregation of the disease (sporadic presentation), investigators have relied on the somewhat laborious candidate gene approach. Fortunately, new insights and technologies have emerged, helping uncover the genetic factors that contribute to CHD.

Introduction: Bicuspid aortic valve (BAV) is common in Turner syndrome (TS). In adult TS, 82-95% of BAVs have fusion of the right and left coronary leaflets. Data in fetal stages are scarce. The purpose of this study was to gain insight into aortic valve morphology and associated cardiovascular abnormalities in a fetal TS cohort with adverse outcome early in development. Material and Methods: We studied post-mortem heart specimens of 36 TS fetuses and 1 TS newborn. Results: BAV was present in 28 (76%) hearts. BAVs showed fusion of the right and left coronary leaflet (type 1 BAV) in 61%, and fusion of the right coronary and non-coronary leaflet (type 2 BAV) in 39%. There were no significant differences in occurrence of additional cardiovascular abnormalities between type 1 and type 2 BAV. However, all type 2 BAV hearts showed ascending aorta hypoplasia and tubular hypoplasia of the B segment, as opposed to only 55 and 64% of type 1 BAV hearts, respectively. Discussion: The proportion of type 2 BAV seems higher in TS fetuses than in adults. Fetal type 2 BAV hearts all had severe aortic pathology, possibly contributing to a worse prognosis of type 2 than type 1 BAV in TS.

Background The T gene (brachyury gene) is the founding member of the T-box family of transcription factors and is vital for the formation and differentiation of the mesoderm and the axial development of all vertebrates.Results We report here on four patients from three consanguineous families exhibiting sacral agenesis, a persistent notochordal canal and abnormal ossification of the vertebral bodies, and the identification and characterisation of their underlying genetic defect. Given the consanguineous nature and the similarity of the phenotypes between the three families, we performed homozygosity mapping and identified a common 4.1Mb homozygous region on chromosome 6q27, containing T, brachyury homologue (mouse) or T. Sequencing of T in the affected individuals led to the identification of a homozygous missense mutation, p.H171R, in the highly conserved T-box. The homozygous mutation results in diminished DNA binding, increased cell growth, and interferes with the normal expression of genes involved in ossification, notochord maintenance and axial mesoderm development.Conclusions We have identified a shared homozygous mutation in three families in T and linked it to a novel syndrome consisting of sacral agenesis, a persistent notochordal canal and abnormal ossification of the vertebral bodies. We suggest that screening for the ossification of the vertebrae is warranted in patients with sacral agenesis to evaluate the possible causal involvement of T.

Tetralogy of Fallot (TOF) (OMIM #187500) is the most frequent conotruncal congenital heart defect (CHD) with a range of intra- and extracardiac phenotypes. TBX5 is a transcription factor with well-defined roles in heart and forelimb development, and mutations in TBX5 are associated with Holt-Oram syndrome (HOS) (OMIM#142900). Here we report on the screening of 94 TOF patients for mutations in TBX5, NKX2.5 and GATA4 genes. We identified two heterozygous mutations in TBX5. One mutation was detected in a Moroccan patient with TOF, a large ostium secundum atrial septal defect and complete atrioventricular block, and features of HOS including bilateral triphalangeal thumbs and fifth finger clinodactyly. This patient carried a previously described de novo, stop codon mutation (p.R279X) located in exon 8 causing a premature truncated protein. In a second patient from Italy with TOF, ostium secundum atrial septal defect and progressive arrhythmic changes on ECG, we identified a maternally inherited novel mutation in exon 9, which caused a substitution of a serine with a leucine at amino acid position 372 (p.S372L, c.1115C>T). The mother's clinical evaluation demonstrated frequent ventricular extrasystoles and an atrial septal aneurysm. Physical examination and radiographs of the hands showed no apparent skeletal defects in either child or mother. Molecular evaluation of the p.S372L mutation demonstrated a gain-of-function phenotype. We also review the literature on the co-occurrence of TOF and HOS, highlighting its relevance. This is the first systematic screening for TBX5 mutations in TOF patients which detected mutations in two of 94 (2.1%) patients. © 2014 Wiley Periodicals, Inc

To follow a candidate gene approach for the involvement of the KCND2 and KCND3 genes (Kv4.2 and Kv4.3) in the pathogenesis of the long QT syndrome (LQTS) and Brugada syndrome, it is necessary to determine the genomic organisation of KCND2 and KCND3. We therefore resolved the intron-exon boundaries and flanking intronic sequences and found that KCND2 consisted of six exons and KCND3 of seven exons. Subsequently, we designed the oligonucleotide primers needed for amplifying the coding exons of both KCND2 and KCND3 and established conditions for polymerase chain reaction amplification of each exon from genomic DNA. Furthermore, the chromosomal localisation of KCND2 and KCND3 was determined as 7q31 and 1p13.2, respectively. This information should facilitate the systematic screening of KCND2 and KCND3 exons for mutations in (inherited) arrhythmia syndromes, such as LQTS and Brugada.

Background. To investigate late cardiotoxicity in childhood acute lymphoblastic leukemia (ALL) survivors after induction treatment with or without daunorubicin (DNR; 25 mg/m(2), i.v., weekly, x4, cumulative dose 100 mg/m(2)). Procedure, Cardiac function was assessed in 90 event-free survivors of childhood ALL, 11.4-17.8 years (median 14.8 years) after treatment according to the DCLSG protocol ALL V. In this protocol patients were randomized to receive (group B) or not to receive (group A) DNR 25 mg/m(2)/week i.v. during the first 4 weeks of induction treatment. Age at diagnosis was 1.2-14.9 years (median 4.5 years). The cardiac evaluation consisted of a history, physical examination, electrocardiogram (ECC), 24 hr ambulatory EGG, and echocardiography. Results. Electrocardiographic data, arrhythmias, left ventricular dimensions, left ventricular contractility, wall stress, and diastolic function were within normal limits in both groups. No difference could be shown between data from group A (n = 40) and group B (n = 50). Conclusions. No late cardiac damage was demonstrated in childhood ALL survivors after induction treatment including a cumulative dose of 100 mg/m(2) DNR, compared to survivors who received the same treatment but without DNR. DNR 100 mg/m(2) given in 4 doses of 25 mg/m(2)/week appears to be a safe dose in induction treatment of ALL. 2000 Wiley-Liss, Inc.

For adult patients with congenital heart disease (CHD), knowledge about the origin and inheritance of their CHD is important. Clinical geneticists may play a significant role in their care. We explored the diagnostic yield of clinical genetic consultation of adult CHD patients, patients' motivations for the consultation, implications for reproductive decisions, patients' evaluation of the impact of provided information, and satisfaction with counseling. Chart review was performed on all adult patients referred for CHD to our clinical genetics department between 2000 and 2011 (n=90). Additionally, a questionnaire was sent to those patients referred between 2005 and 2011 (n=64), of which 46 useful questionnaires were returned (72% response). Of patients without an etiological diagnosis at referral (n=83), 17 (20%) were eventually diagnosed with syndromic CHD, 6 (7%) with nonsyndromic monogenetic CHD and 45 (54%) with nonsyndromic multifactorial CHD. The diagnosis remained undetermined in 15 (18%) patients. Half of patients who returned the questionnaire had purposefully postponed having children until after genetic consultation and 13% had changed their mind about having children or not after the consultation. Counseling was valued positively. In this study, we showed the added value of clinical genetic consultation in the care for adult CHD patients: it improves diagnostics by establishing an etiological diagnosis and associated recurrence risk in a substantial proportion of patients and leads to more informed reproductive decisions. With new genetic testing technologies an etiological diagnosis may be established in an increasing number of patients in the near future.

Left ventricular noncompaction (LVNC) is a relatively common genetic cardiomyopathy, characterized by prominent trabeculations with deep intertrabecular recesses in mainly the left ventricle. Although LVNC often occurs in an isolated entity, it may also be present in various types of congenital heart disease (CHD). The most prevalent CHD in LVNC is Ebstein anomaly, which is a rare form of CHD characterized by apical displacement and partial fusion of the septal and posterior leaflet of the tricuspid valve with the ventricular septum. Several reports of sporadic as well as familial cases of Ebstein anomaly associated with LVNC have been reported. Recent studies identified mutations in the MYH7 gene, encoding the sarcomeric β-myosin heavy chain protein, in patients harboring this specific phenotype. Here, we will review the association between Ebstein anomaly, LVNC and mutations in MYH7, which seems to represent a subtype of Ebstein anomaly with autosomal dominant inheritance and variable penetrance.

We conducted a genome-wide association study to search for risk alleles associated with Tetralogy of Fallot (TOF), using a northern European discovery set of 835 cases and 5159 controls. A region on chromosome 12q24 was associated (P = 1.4 × 10-7) and replicated convincingly (P = 3.9 × 10-5) in 798 cases and 2931 controls [per allele odds ratio (OR) = 1.27 in replication cohort, P = 7.7 × 10-11 in combined populations]. Single nucleotide polymorphisms in the glypican 5 gene on chromosome 13q32 were also associated (P = 1.7 × 10-7) and replicated convincingly (P = 1.2 × 10-5) in 789 cases and 2927 controls (per allele OR = 1.31 in replication cohort, P = 3.03 × 10-11 in combined populations). Four additional regions on chromosomes 10, 15 and 16 showed suggestive association accompanied by nominal replication. This study, the first genome-wide association study of a congenital heart malformation phenotype, provides evidence that common genetic variation influences the risk of TOF.

Ebstein's anomaly is a rare congenital heart malformation characterised by adherence of the septal and posterior leaflets of the tricuspid valve to the underlying myocardium. Associated abnormalities of left ventricular morphology and function including left ventricular noncompaction (LVNC) have been observed. An association between Ebstein's anomaly with LVNC and mutations in the sarcomeric protein gene MYH7, encoding β -myosin heavy chain, has been shown by recent studies. This might represent a specific subtype of Ebstein's anomaly with a Mendelian inheritance pattern. In this review we discuss the association of MYH7 mutations with Ebstein's anomaly and LVNC and its implications for the clinical care for patients and their family members.

Background— Association between the C677T polymorphism of the methylene tetrahydrofolate reductase ( MTHFR ) gene and congenital heart disease (CHD) is contentious. Methods and Results— We compared genotypes between CHD cases and controls and between mothers of CHD cases and controls. We placed our results in context by conducting meta-analyses of previously published studies. Among 5814 cases with primary genotype data and 10 056 controls, there was no evidence of association between MTHFR C677T genotype and CHD risk (odds ratio [OR], 0.96 [95% confidence interval, 0.87–1.07]). A random-effects meta-analysis of all studies (involving 7697 cases and 13 125 controls) suggested the presence of association (OR, 1.25 [95% confidence interval, 1.03–1.51]; P =0.022) but with substantial heterogeneity among contributing studies (I 2 =64.4%) and evidence of publication bias. Meta-analysis of large studies only (defined by a variance of the log OR 2 =0). Moreover, meta-analysis of 1781 mothers of CHD cases (829 of whom were genotyped in this study) and 19 861 controls revealed no evidence of association between maternal C677T genotype and risk of CHD in offspring (OR, 1.13 [95% confidence interval, 0.87–1.47]). There was no significant association between MTHFR genotype and CHD risk in large studies from regions with different levels of dietary folate. Conclusions— The MTHFR C677T polymorphism, which directly influences plasma folate levels, is not associated with CHD risk. Publication biases appear to substantially contaminate the literature with regard to this genetic association.

NKX2-5 is a homeodomain-containing transcription factor implied in both heart and thyroid development. Numerous mutations in NKX2-5 have been reported in individuals with congenital heart disease (CHD), but recently a select few have been associated with thyroid dysgenesis, among which the p.A119S variation. We sequenced NKX2-5 in 303 sporadic CHD patients and 38 families with at least two individuals with CHD. The p.A119S variation was identified in two unrelated patients: one was found in the proband of a family with four affected individuals with CHD and the other in a sporadic CHD patient. Clinical evaluation of heart and thyroid showed that the mutation did not segregate with CHD in the familial case, nor did any of the seven mutation carriers have thyroid abnormalities. We tested the functional consequences of the p.A119S variation in a cellular context by performing transactivation assays with promoters relevant for both heart and thyroid development in rat heart derived H10 cells and HELA cells. There was no difference between wildtype NKX2-5 and p.A119S NKX2-5 in activation of the investigated promoters in both cell lines. Additionally, we reviewed the current literature on the topic, showing that there is no clear evidence for a major pathogenic role of NKX2-5 mutations in thyroid dysgenesis. In conclusion, our study demonstrates that p.A119S does not cause CHD or TD and that it is a rare variation that behaves equal to wildtype NKX2-5. Furthermore, given the wealth of published evidence, we suggest that NKX2-5 mutations do not play a major pathogenic role in thyroid dysgenesis, and that genetic testing of NKX2-5 in TD is not warranted.

We carried out a genome-wide association study (GWAS) of congenital heart disease (CHD). Our discovery cohort comprised 1,995 CHD cases and 5,159 controls and included affected individuals from each of the 3 major clinical CHD categories (with septal, obstructive and cyanotic defects). When all CHD phenotypes were considered together, no region achieved genome-wide significant association. However, a region on chromosome 4p16, adjacent to the MSX1 and STX18 genes, was associated (P = 9.5 × 10 -7) with the risk of ostium secundum atrial septal defect (ASD) in the discovery cohort (N = 340 cases), and this association was replicated in a further 417 ASD cases and 2,520 controls (replication P = 5.0 × 10 -5; odds ratio (OR) in replication cohort = 1.40, 95% confidence interval (CI) = 1.19-1.65; combined P = 2.6 × 10 -10). Genotype accounted for ∼9% of the population-attributable risk of ASD. © 2013 Nature America, Inc. All rights reserved.

This editorial refers to ‘A novel gain-of-function KCNJ2 mutation associated with short-QT syndrome impairs inward rectification of Kir2.1 currents’ by T. Hattori et al ., pp. 666–673, this issue. The short QT syndrome (SQTS) is a recently recognized cardiac channelopathy characterized by a shortened QT interval in the electrocardiogram (ECG). It is associated with a high incidence of atrial fibrillation (AF), syncope, and sudden death in the absence of structural cardiac abnormalities. Gussak et al. first described the syndrome in 2000 within the context of an isolated case of sudden cardiac death in a young female and the presence of early-onset AF in a separate family.1 Cardiac workup demonstrated a structurally normal heart in affected individuals, but a remarkable short QTc interval on the ECG ranging between 248 and 300 ms. These first studies led to the emerging recognition of SQTS as a distinct clinical entity and were followed by reports on similar cases (reviewed in Gollob et al. 2). The diagnosis of SQTS is somewhat complicated as QT intervals overlap between affected cases and apparently healthy subjects. The presence of a short QT interval by itself is not always predictive of an increased arrhythmic risk and therefore should not invariably lead to a diagnosis of SQTS.3 To address this, Gollob et al. 2 recently proposed a set of formal diagnostic criteria …

The endothermic state of mammals and birds requires high heart rates to accommodate the high rates of oxygen consumption. These high heart rates are driven by very similar conduction systems consisting of an atrioventricular node that slows the electrical impulse and a His-Purkinje system that efficiently activates the ventricular chambers. While ectothermic vertebrates have similar contraction patterns, they do not possess anatomical evidence for a conduction system. This lack amongst extant ectotherms is surprising because mammals and birds evolved independently from reptile-like ancestors. Using conserved genetic markers, we found that the conduction system design of lizard (Anolis carolinensis and A. sagrei), frog (Xenopus laevis) and zebrafish (Danio rerio) adults is strikingly similar to that of embryos of mammals (mouse Mus musculus, and man) and chicken (Gallus gallus). Thus, in ectothermic adults, the slow conducting atrioventricular canal muscle is present, no fibrous insulating plane is formed, and the spongy ventricle serves the dual purpose of conduction and contraction. Optical mapping showed base-to-apex activation of the ventricles of the ectothermic animals, similar to the activation pattern of mammalian and avian embryonic ventricles and to the His-Purkinje systems of the formed hearts. Mammalian and avian ventricles uniquely develop thick compact walls and septum and, hence, form a discrete ventricular conduction system from the embryonic spongy ventricle. Our study uncovers the evolutionary building plan of heart and indicates that the building blocks of the conduction system of adult ectothermic vertebrates and embryos of endotherms are similar.

Background— Cardiac conduction disease is a clinically and genetically heterogeneous disorder characterized by defects in electrical impulse generation and conduction and is associated with sudden cardiac death. Methods and Results— We studied a 4-generation family with autosomal dominant progressive cardiac conduction disease, including atrioventricular conduction block and sinus bradycardia, atrial arrhythmias, and sudden death. Genome-wide linkage analysis mapped the disease locus to chromosome 1p22-q21. Multiplex ligation-dependent probe amplification analysis of the LMNA gene, which encodes the nuclear-envelope protein lamin A/C, revealed a novel gene rearrangement involving a 24-bp inversion flanked by a 3.8-kb deletion upstream and a 7.8-kb deletion downstream. The presence of short inverted sequence homologies at the breakpoint junctions suggested a mutational event involving serial replication slippage in trans during DNA replication. Conclusions— We identified for the first time a complex LMNA gene rearrangement involving a double deletion in a 4-generation Dutch family with progressive conduction system disease. Our findings underscore the fact that if conventional polymerase chain reaction–based direct sequencing approaches for LMNA analysis are negative in suggestive pedigrees, mutation detection techniques capable of detecting gross genomic lesions involving deletions and insertions should be considered.

Background— Ebstein anomaly is a rare congenital heart malformation characterized by adherence of the septal and posterior leaflets of the tricuspid valve to the underlying myocardium. An association between Ebstein anomaly with left ventricular noncompaction (LVNC) and mutations in MYH7 encoding β-myosin heavy chain has been shown; in this report, we have screened for MYH7 mutations in a cohort of probands with Ebstein anomaly in a large population-based study. Methods and Results— Mutational analysis in a cohort of 141 unrelated probands with Ebstein anomaly was performed by next-generation sequencing and direct DNA sequencing of MYH7 . Heterozygous mutations were identified in 8 of 141 samples (6%). Seven distinct mutations were found; 5 were novel and 2 were known to cause hypertrophic cardiomyopathy. All mutations except for 1 3-bp deletion were missense mutations; 1 was a de novo change. Mutation-positive probands and family members showed various congenital heart malformations as well as LVNC. Among 8 mutation-positive probands, 6 had LVNC, whereas among 133 mutation-negative probands, none had LVNC. The frequency of MYH7 mutations was significantly different between probands with and without LVNC accompanying Ebstein anomaly ( P MYH7 mutation in the pedigrees of 3 of the probands, 1 of which also included another individual with Ebstein anomaly. Conclusions— Ebstein anomaly is a congenital heart malformation that is associated with mutations in MYH7 . MYH7 mutations are predominantly found in Ebstein anomaly associated with LVNC and may warrant genetic testing and family evaluation in this subset of patients.

Mutations in the human cardiac calsequestrin gene (CASQ2) are linked to catecholaminergic polymorphic ventricular tachycardia (CPVT-2). This inherited disorder is characterized by life-threatening arrhythmias induced by physical and emotional stress in young patients Here we identified a novel heterozygous missense mutation (K206N) in the CASQ2 gene in a symptomatic family in which one member died of cardiac arrest. The functional properties of CSQ(K206N) were investigated in comparison to the wild-type form of CASQ2 (CSQ(WT)) by expression in eukaryotic cell lines and neonatal mouse myocytes The mutation created an additional N-glycosylation site resulting in a higher molecular weight form of the recombinant protein on immunoblots The mutation reduced the Ca2+ binding capacity of the protein and exhibited an altered aggregation state Consistently, CSQ(K206N)-expressing myocytes exhibited an impaired response to caffeine administration, suggesting a lower Ca2+ load of the sarcoplasmic reticulum (SR) The interaction of the mutated CSQ with triadin and the protein levels of the ryanodine receptor were unchanged but the maximal specific [H-3]ryanodine binding was increased in CSQ(K206N)-expressing myocytes, suggesting a higher opening state of the SR Ca2+ release channel Myocytes with expression of CSQ(K206N) showed a higher rate of spontaneous SR Ca2+ releases under basal conditions and after beta-adrenergic stimulation. We conclude that CSQ(K206N) caused a reduced Ca2+ binding leading to an abnormal regulation of intracellular Ca2+ in myocytes. This may then contribute to the increased propensity to trigger spontaneous Ca2+ transients in CSQ(K206N)-expressing myocytes (C) 2010 Elsevier Ltd. All rights reserved

Atrial fibrillation (AF) is the most common cardiac arrhythmia encountered in clinical practice. The abnormal rhythm is associated not only with a variety of symptoms, such as palpitations, dizziness, or shortness of breath, but also with increased risk of stroke, heart failure, and mortality. A genetic predisposition is suggested by the fact that the relative risk for the development of AF is estimated at 85% in individuals with at least one parent with a history of AF. Current therapeutic strategies include control of rate or rhythm with medication and catheter ablation procedures. Especially in the pathophysiology of paroxysmal AF, ectopic electrical activity originating in the myocardial sleeves surrounding the pulmonary veins is considered causal. In these cases, ablation is applied to isolate the pulmonary venous myocardium from the remainder of the left atrial myocardium. Other recent evidence has shown that genetic and developmental defects can be involved in the development of AF. In this review, it is our aim to discuss the possible underlying causes of AF from a combined genetic and cardiac developmental view.

Data on the prevalence of congenital heart defects (CHD) in neuroblastoma patients are inconsistent. If CHD are more common in neuroblastoma patients than in the general population, cardiac screening might be warranted. In this study we used echocardiography to determine the prevalence of CHD in a single centre cohort of surviving neuroblastoma patients. In addition, we performed a systematic review of the literature. Echocardiography was performed in 119 of 133 patients (89.5%). Only two patients (1.7%) had CHD. The prevalence of CHD was not significantly different from a previously published control group of 192 leukaemia patients examined by echocardiography (P=0.49). Literature search revealed 17 studies, showing prevalence rates of CHD in neuroblastoma patients ranging from 0 to 20%. Prevalence was less than 3.6% in the majority of studies. Most studies lacked information on validity. We conclude that current evidence does not support standard cardiac screening in all patients with neuroblastoma.

The cardiovascular system is the first organ system to form and function in the developing embryo. The function of the system is to continuously pump blood throughout the body for an entire lifetime. The adult heart, as the main pump in this system, performs roughly two thousand million cycles (2.3 × 109) in a typical lifetime. This continuous cycle is necessary to supply the whole body and all of its organs with oxygen and nutrients. Realization of this requires that the heart relaxes so that its chambers, the atria and ventricles, can fill with blood and then contract to propel the blood throughout the body. To achieve this, an intricate and complex organ developed, containing multiple chambers, nodes, valves, and electrical and force-producing components. In contrast, in primitive chordates and early vertebrate embryos the heart merely constitutes a myocardial mantle enfolding a ventral aorta, in which the blood is propelled by peristaltic contractions. The cardiomyocytes of such a primitive heart can be considered as “nodal” cells as they display automaticity and are poorly coupled, resulting in slow propagation of the depolarizing impulse and a matching peristaltic contraction. Eventually, the development of polarity, specifically, dominant pacemaker activity at the intake of the heart, led to the evolution of a one-way pump. Although dominant pacemaker activity implies development of sinus node function, only in mammals does a morphologically distinct node actually develop.1 The addition of highly localized, fast conducting cardiac chambers to the straight heart tube is an evolutionary novel event, and resulted in the four-chambered hearts of birds and mammals with synchronous contraction for a dual circulation. Interestingly, concomitant with the formation of chambers, an adult type of electrocardiogram (ECG) can already be monitored in the embryo (Figure 2-1).2 Thus, cardiac design, e.g., the positioning of the atrial and ventricular chambers within the straight heart tube, rather than the invention of nodes, principally explains the coordinated activation of the heart reflected in the ECG. To address the question why some areas of the embryonic heart tube do not participate in the formation of atrial or ventricular working myocardium and mature in a nodal direction, we suggest that the chamber-specific program of gene expression is specifically repressed by T-box factors and by other transcriptional repressors. Consequently, aberrant expression of these factors might be at the basis of ectopic automaticity and congenital malformations of the cardiac conduction system in the formed human heart.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an uncommon heritable disease presenting with syncope or sudden cardiac death. Two genes involved in calcium homeostasis, the ryanodine receptor gene and the calsequestrin 2 (CASQ2) gene, have been implicated in this disease. We describe a young man presenting with exercise-induced syncope, clinically diagnosed as CPVT. Genetic analysis revealed two mutations, p.Y55C (C.164A>G) and p.P308L (c.923C>T), in the CASQ2 gene. Subsequent familial analysis indicates a compound heterozygous form of inheritance. (PACE 2008; 31:916-919). © 2008, The Authors. Journal compilation © 2008, Blackwell Publishing, Inc.

Holt–Oram syndrome (HOS) is a heart/hand syndrome clinically characterized by upper limb and cardiac malformations. Mutations in T-box transcription factor 5 ( TBX5 ) underlie this syndrome. Here, we describe a large atypical HOS family in which affected patients have mild skeletal deformations and paroxysmal atrial fibrillation, but few have congenital heart disease. Sequencing of TBX5 revealed a novel mutation, c.373G>A, resulting in the missense mutation p.Gly125Arg, in all investigated affected family members, cosegregating with the disease. We demonstrate that the mutation results in normal Nkx2-5 interaction, is correctly targeted to the nucleus, has significantly enhanced DNA binding and activation of both the Nppa ( Anf ) and Cx40 promoter, and significantly augments expression of Nppa , Cx40 , Kcnj2 , and Tbx3 in comparison with wild-type TBX5. Thus, contrary to previously published HOS mutations, the p.G125R TBX5 mutation results in a gain-of-function. We speculate that the gain-of-function mechanism underlies the mild skeletal phenotype and paroxysmal atrial fibrillation and suggest a possible role of TBX5 in the development of (paroxysmal) atrial fibrillation based on a gain-of-function either through a direct stimulation of target genes via TBX5 or indirectly via TBX5 stimulated TBX3. These findings may warrant a renewed look at the phenotypes of families and individuals hitherto not classified as HOS or as atypical but presenting with paroxysmal atrial fibrillation, because these may possibly be the result of additional TBX5 gain-of-function mutations.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmogenic disease characterized by adrenergic-induced arrhythmias in the form of bidirectional and PVT. CPVT is a distinct clinical entity associated with a high mortality rate of up to 50% by the age of 30 yr. Recently, the molecular diagnostics of this disease have become increasingly important because underlying mutations can be found in more than 60% of the identified CPVT patients. Along with the fact that treatment with beta-blockers has a favorable outcome in CPVT patients, and given the risk of sudden death, the identification of causative mutations in CPVT is important because it can greatly augment early diagnosis and subsequent preventive strategies. In this chapter, we describe the molecular diagnostics, as performed in our lab, of the three genes known to be involved in CPVT, the cardiac ryanodine receptor gene, the cardiac calsequestrin gene, and the inwardly rectifying potassium channel KCNJ2.

Catecholinergic ventricular tachycardia is an adrenergic induced polymorphic ventricular arrhythmia. It occurs in infancy and is responsible for syncope and sudden death in the absence of any morphological cardiac abnormality. Without treatment the mortality in catecholinergic ventricular tachycardia is very high. We report genetic and clinical data from 25 cases of catecholinergic ventricular tachycardia referred with syncope (n=19) or resuscitated sudden death during exercise (n=6). A family history from the 25 families identified 41 apparent subjects considered as being clinically affected, with an average age of 30 +/- 10 years (11 to 62 years). Analysis of the RyR2 gene showed mutations in 13 of the 25 cases and in 39 of apparent subjects. With betablocker treatment (nadolol: 1.6 +/- 0.15 mg/kg), 96% of patients remained asymptomatic over an average follow-up of between 7.5 +/- 1.5 years, although some of them continued to display polymorphic ventricular extrasystoles on exercise. Nevertheless, 12% of the cases suffered sudden death or further syncope during follow-up. An automatic defibrillator was implanted in 2 patients who had a RyR2 mutation. High dose betablockers are effective in preventing serious rhythm disturbance in children. In adolescence, implanting an automatic defibrillator should be discussed in cases with a history of syncope or resuscitated sudden death. We confirm the importance of genetic studies in these families at high risk of sudden death.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare arrhythmogenic disorder characterized by syncopal events and sudden cardiac death at a young age during physical stress or emotion, in the absence of structural heart disease. We report the first nonsense mutations in the cardiac calsequestrin gene, CASQ2 , in three CPVT families. The three mutations, a nonsense R33X, a splicing 532+1 G>A, and a 1-bp deletion, 62delA, are thought to induce premature stop codons. Two patients who experienced syncopes before the age of 7 years were homozygous carriers, suggesting a complete absence of calsequestrin 2. One patient was heterozygous for the stop codon and experienced syncopes from the age of 11 years. Despite the different mutations, there is little phenotypic variation of CPVT for the CASQ2 mutations. Of the 16 heterozygous carriers of these various mutations, 14 were devoid of clinical symptoms or ECG anomalies, whereas 2 of them had ventricular arrhythmias at ECG on exercise tests. In line with this, the diagnosis of the probands was difficult because of the absence of a positive family history. In conclusion, these additional three CASQ2 CPVT families suggest that CASQ2 mutations are more common than previously thought and produce a severe form of CPVT. The full text of this article is available at http://www.circresaha.org.

In 1980, the Dutch Childhood Leukemia Study Group (DCLSG) conducted a study for treatment of acute nonlymphoblastic leukemia (ANLL) consisting of 12 injections of high dose cytarabine (HDARA-C) followed by 2 injections of doxorubicin as the only treatment for childhood ANLL. Children who reached complete remission (CR) received either allogeneic bone marrow transplantation (BMT) or no further treatment. CR rate was 71%. The event free interval (EFI) for children receiving only induction treatment was 18% [1]. In the next study, ANLL-82, the same induction treatment was used, consisting of 12 injections of HDARA-C and one of doxorubicin; these injections were individually scheduled based on cell kinetic properties of the leukemic cells.

Background Ebstein9s anomaly is a rare congenital heart malformation characterised by adherence of the septal and posterior leaflets of the tricuspid valve to the underlying myocardium. As there have been reports of abnormal left ventricular morphology and function in patients with Ebstein9s anomaly we hypothesised that mutations in the β-myosin heavy chain (MYH7) may be associated with Ebstein9s anomaly. Methods MYH7 mutation analysis was undertaken in 141 unrelated affected individuals with Ebstein9s anomaly using next-generation sequencing on the 454 platform. 64 probands had no associated cardiac anomalies. The most common associated cardiac malformation were atrial septal defect (48 probands) and left ventricular non-compaction (LVNC) (7 probands). Where mutations were discovered, family studies were undertaken and the segregation of the mutation with disease was investigated. Results Heterozygous mutations were identified in eight of the probands including six of the seven with LVNC. Two patients had the same mutation; of the seven distinct mutations, five were novel (four missense changes and an in-frame deletion) and two have been previously reported in patients with hypertrophic cardiomyopathy. Family studies revealed additional members with LVNC for three of the probands, one of whom also had a relative with Ebstein9s anomaly. In these three pedigrees the mutation segregated with disease. Conclusions Mutations in MYH7 occur relatively frequently in Ebstein9s anomaly accompanied by LVNC. This study is another example of mutations in a sarcomere protein causing congenital heart malformation.

We thank Digilio et al for their interest in our paper, showing that 22q11.2 deletion syndrome (22q11.2DS) is underrecognised in adults with tetralogy of Fallot (TOF) and with pulmonary atresia (PA)/ventricular septal defect (VSD).1 Digilio et al disagree with our recommendation to consider genetic testing for the syndrome in all adults with TOF and PA/VSD. Rather they propose to reserve this for patients with associated ‘classic’ or ‘subtle’ extracardiac anomalies and to …

[[ Cardiovascular Research, Volume 88, Issue 1, 1 October 2010, Pages 130–139; doi:101093/cvr/cvq178. ]][1] The original version of this article was incorrect: Inge B. Mathijssen was not included as a co-author. The online version of the article has been corrected, but the print version remains

10032 Background: In childhood cancer survivors (CCS), cardiac dysfunction has been mainly characterized by systolic dysfunction (SysDfx). However, both SysDfx and diastolic dysfunction (DiasDfx) a...

Background: Dilated cardiomyopathy (DCM) is characterized by idiopathic dilatation and systolic contractile dysfunction of the ventricle(s) leading to an impaired systolic function. The origin of DCM is heterogeneous, but genetic transmission of the disease accounts for up to 50% of the cases. Mutations in alpha-tropomyosin (TPM1), a thin filament protein involved in structural and regulatory roles in muscle cells, are associated with hypertrophic cardiomyopathy (HCM) and very rarely with DCM. Methods and results: Here we present a large four-generation family in which DCM is inherited as an autosomal dominant trait. Six family members have a cardiomyopathy with the age of diagnosis ranging from 5 months to 52 years. The youngest affected was diagnosed with dilated and non-compaction cardiomyopathy (NCCM) and died at the age of five. Three additional children died young of suspected heart problems. We mapped the phenotype to chromosome 15 and subsequently identified a missense mutation in TPM1, resulting in a p.D84N amino acid substitution. In addition we sequenced 23 HCM/DCM genes using next generation sequencing. The TPM1 p.D84N was the only mutation identified. The mutation co-segregates with all clinically affected family members and significantly weakens the binding of tropomyosin to actin by 25%. Conclusions: We show that a mutation in TPM1 is associated with DCM and a lethal, early onset form of NCCM, probably as a result of diminished actin binding caused by weakened charge–charge interactions. Consequently, the screening of TPM1 in patients and families with DCM and/or (severe, early onset forms of) NCCM is warranted. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.

Congenital heart defects (CHDs) are the most common major developmental anomalies and the most frequent cause for perinatal mortality, but their etiology remains often obscure. We identified a locus for CHDs on 6q24-q25. Genotype-phenotype correlations in 12 patients carrying a chromosomal deletion on 6q delineated a critical 850 kb region on 6q25.1 harboring five genes. Bioinformatics prioritization of candidate genes in this locus for a role in CHDs identified the TGF-beta-activated kinase 1/MAP3K7 binding protein 2 gene (TAB2) as the top-ranking candidate gene. A role for this candidate gene in cardiac development was further supported by its conserved expression in the developing human and zebrafish heart. Moreover, a critical, dosage-sensitive role during development was demonstrated by the cardiac defects observed upon titrated knockdown of tab2 expression in zebrafish embryos. To definitively confirm the role of this candidate gene in CHDs, we performed mutation analysis of TAB2 in 402 patients with a CHD, which revealed two evolutionarily conserved missense mutations. Finally, a balanced translocation was identified, cosegregating with familial CHD. Mapping of the breakpoints demonstrated that this translocation disrupts TAB2. Taken together, these data clearly demonstrate a role for TAB2 in human cardiac development. ispartof: American Journal of Human Genetics vol:86 issue:6 pages:839-849 ispartof: location:United States status: published

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an arrhythmogenic disease characterized by adrenergic-induced arrhythmias in the form of bidirectional and PVT. CPVT is a distinct clinical entity associated with a high mortality rate of up to 50% by the age of 30 yr. Recently, the molecular diagnostics of this disease have become increasingly important because underlying mutations can be found in more than 60% of the identified CPVT patients. Along with the fact that treatment with beta-blockers has a favorable outcome in CPVT patients, and given the risk of sudden death, the identification of causative mutations in CPVT is important because it can greatly augment early diagnosis and subsequent preventive strategies. In this chapter, we describe the molecular diagnostics, as performed in our lab, of the three genes known to be involved in CPVT, the cardiac ryanodine receptor gene, the cardiac calsequestrin gene, and the inwardly rectifying potassium channel KCNJ2

Abstract —Mutations in SCN5A , the gene encoding the cardiac Na + channel, have been identified in 2 distinct diseases associated with sudden death: one form of the long-QT syndrome (LQT 3 ) and the Brugada syndrome. We have screened SCN5A in a large 8-generation kindred characterized by a high incidence of nocturnal sudden death, and QT-interval prolongation and the “Brugada ECG” occurring in the same subjects. An insertion of 3 nucleotides (TGA) at position 5537, predicted to cause an insertion of aspartic acid (1795insD) in the C-terminal domain of the protein, was linked to the phenotype and was identified in all electrocardiographically affected family members. ECGs were obtained from 79 adults with a defined genetic status (carriers, n=43; noncarriers, n=36). In affected individuals, PR and QRS durations and QT intervals are prolonged ( P P + channels in Xenopus oocytes revealed that the 1795insD mutation gives rise to a 7.3-mV negative shift of the steady-state inactivation curve and an 8.1-mV positive shift of the steady-state activation curve. The functional consequence of both shifts is likely to be a reduced Na + current during the upstroke of the action potential. LQT 3 and Brugada syndrome are allelic disorders but may also share a common genotype.