Brugada Syndrome and Pulmonary Atresia with Intact Interventricular Septum: Fortuitous Finding or New Genetic Connection?

Brugada syndrome is a rare arrhythmogenic syndrome associated mainly with pathogenic variants in the SCN5A gene. Right ventricle outflow tract fibrosis has been reported in some cases of patients diagnosed with Brugada syndrome. Pulmonary atresia with an intact ventricular septum is characterized by the lack of a functional pulmonary valve, due to the underdevelopment of the right ventricle outflow tract. We report, for the first time, a 4-year-old boy with pulmonary atresia with an intact ventricular septum who harbored a pathogenic de novo variant in SCN5A, and the ajmaline test unmasked a type-1 Brugada pattern. We suggest that deleterious variants in the SCN5A gene could be implicated in pulmonary atresia with an intact ventricular septum embryogenesis, leading to overlapping phenotypes.

A loss-of-function mutation p.T256M in NDRG4 is implicated in the pathogenesis of pulmonary atresia with ventricular septal defect (PA/VSD) and tetralogy of Fallot (TOF).

Pulmonary atresia with ventricular septal defect (PA/VSD) is a rare congenital heart disease (CHD) characterized by a lack of luminal continuity and blood flow from either the right ventricle or the pulmonary artery, together with VSDs. The prevalence of PA/VSD is about 0.2% of live births and approximately 2% of CHDs. PA/VSD is similar to tetralogy of Fallot (TOF) in terms of structural and pathological characteristics. The pathogenesis of these two CHDs remains incompletely understood. It was previously reported that N-myc downstream-regulated gene (NDRG)4 is required for myocyte proliferation during early cardiac development. In the present study, we enrolled 80 unrelated patients with PA/VSD or TOF and identified a probably damaging variant p.T256M of NDRG4. The p.T256M variant impaired the proliferation ability of human cardiac myocytes (hCM). Furthermore, the p.T256M variant resulted in G1 and G2 arrest of hCM, followed by an increase in p27 and caspase-9 expression. Our results provide evidence that the p.T256M variant in NDRG4 is a pathogenic variant associated with impaired hCM proliferation and cell-cycle arrest and likely contributes towards the pathogenesis of PA/VSD and TOF.

The 30-Year Outcomes of Tetralogy of Fallot According to Native Anatomy and Genetic Conditions.

BACKGROUND: The reported survival of tetralogy of Fallot (TOF) is > 97%. Patients with pulmonary atresia and/or genetic conditions have worse outcomes, but long-term estimates of survival and morbidity for these TOF subgroups are scarce. The objective of this study was to describe the 30-year outcomes of TOF according to native anatomy and the coexistence of genetic conditions. METHODS: The TRIVIA (Tetralogy of Fallot Research for Improvement of Valve Replacement Intervention: A Bridge Across the Knowledge Gap) study is a retrospective population-based cohort including all TOF subjects born from 1980 to 2015 in Québec. We evaluated all-cause mortality by means of Cox proportional hazards regression, and cumulative mean number of cardiovascular interventions and unplanned hospitalisations with the use of marginal means/rates models. We computed 30-year estimates of outcomes according to TOF types, ie, classic TOF (cTOF) and TOF with pulmonary atresia (TOF-PA), and the presence of genetic conditions. RESULTS: We included 960 subjects. The median follow-up was 17 years (interquartile range, 8-27). Nonsyndromic cTOF subjects had a 30-year survival of 95% and had undergone a mean of 2.8 interventions and 0.5 hospitalisations per subject. In comparison, TOF-PA subjects had a lower 30-year survival of 78% and underwent a mean of 8.1 interventions, with 4 times as many hospitalisations. The presence of a genetic condition was associated with lower survival (< 85% for cTOF and < 60% for TOF-PA) but similar numbers of interventions and hospitalisations. CONCLUSIONS: The anatomic types and the presence of genetic conditions strongly influence the long-term outcomes of TOF. We provided robust 30-year estimates for key markers of prognosis that may be used to improve risk stratification and provide more informed counselling to families.

Single-Cell Transcriptomics of Engineered Cardiac Tissues From Patient-Specific Induced Pluripotent Stem Cell-Derived Cardiomyocytes Reveals Abnormal Developmental Trajectory and Intrinsic Contractile Defects in Hypoplastic Right Heart Syndrome.

Background To understand the intrinsic cardiac developmental and functional abnormalities in pulmonary atresia with intact ventricular septum (PAIVS) free from effects secondary to anatomic defects, we performed and compared single-cell transcriptomic and phenotypic analyses of patient- and healthy subject-derived human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and engineered tissue models. Methods and Results We derived hiPSC lines from 3 patients with PAIVS and 3 healthy subjects and differentiated them into hiPSC-CMs, which were then bioengineered into the human cardiac anisotropic sheet and human cardiac tissue strip custom-designed for electrophysiological and contractile assessments, respectively. Single-cell RNA sequencing (scRNA-seq) of hiPSC-CMs, human cardiac anisotropic sheet, and human cardiac tissue strip was performed to examine the transcriptomic basis for any phenotypic abnormalities using pseudotime and differential expression analyses. Through pseudotime analysis, we demonstrated that bioengineered tissue constructs provide pro-maturational cues to hiPSC-CMs, although the maturation and development were attenuated in PAIVS hiPSC-CMs. Furthermore, reduced contractility and prolonged contractile kinetics were observed with PAIVS human cardiac tissue strips. Consistently, single-cell RNA sequencing of PAIVS human cardiac tissue strips and hiPSC-CMs exhibited diminished expression of cardiac contractile apparatus genes. By contrast, electrophysiological aberrancies were absent in PAIVS human cardiac anisotropic sheets. Conclusions Our findings were the first to reveal intrinsic abnormalities of cardiomyocyte development and function in PAIVS free from secondary effects. We conclude that hiPSC-derived engineered tissues offer a unique method for studying primary cardiac abnormalities and uncovering pathogenic mechanisms that underlie sporadic congenital heart diseases.

22q11.2 deletion syndrome is associated with increased mortality in adults with tetralogy of Fallot and pulmonary atresia with ventricular septal defect.

BACKGROUND: 22q11.2 Deletion syndrome (22q11.2DS) is common in patients with tetralogy of Fallot (TOF) or pulmonary atresia with ventricular septal defect (PA/VSD) and is associated with worse outcomes in children. Whether this impaired prognosis is also translated into adulthood is unknown, as data in adult patients are limited. We aimed to compare long-term outcomes in adults with TOF or PA/VSD both with and without 22q11.2DS. METHODS: This study prospectively followed a nationwide multicenter cohort of TOF or PA/VSD patients with genetically confirmed presence or absence of 22q11.2DS, from inclusion in the Dutch national CONCOR registry for adults with congenital heart disease (CHD) onward. Outcome measures included all-cause mortality, cardiac mortality, need for pulmonary valve replacement (PVR), ventricular arrhythmias (VA), pacemaker implantation, and ICD implantation. RESULTS: In total, 479 patients were included (277 (58%) male, median age 28 [IQR; 21-37] years, 62 (13%) with PA/VSD, 34 (7%) with 22q11.2DS). During a median follow-up of 11 [IQR; 6-13] years, 52 (11%) patients died (8 with 22q11.2DS and 44 without 22q11.2DS). Patients with 22q11.2DS had significant decreased survival after 12 years (76% [95% CI; 62-93]) compared to patients without 22q11.2DS (89% [95% CI; 86-92], p = 0.008). 22q11.2DS was associated with increased risk of all-cause mortality and cardiac-mortality, independent of age, sex, and PA/VSD. No association was found between 22q11.2DS and late complications i.e. PVR, VA, pacemaker, or ICD implantation. CONCLUSIONS: Adults with TOF or PA/VSD with 22q11.2DS have a significantly worse survival than adults without this deletion. In patients with TOF or PA/VSD, genetic analysis for the presence of 22q11.2DS is important for risk stratification and genetic counseling.

A rare mosaic 22q11.2 microdeletion identified in a Chinese family with recurrent fetal conotruncal defects.

BACKGROUND: 22q11 deletion syndrome (22qDS) is caused by deletion of chromosome region 22q11.2. However, mosaic cases with 22q11.2 deletion syndrome (22q11.2DS) are rarely reported. METHODS: Chromosomal microarray analysis (CMA) and fluorescence in situ hybridization fluorescence in situ hybridization (FISH) were performed to analyze the copy number alterations. Clinical examinations related to 22q11.2DS were performed on the carrier in this family. RESULTS: A healthy female in a Chinese family with a history of two pregnancies with conotruncal defects, one with pulmonary atresia (PA) and another with Tetralogy of Fallot (TOF) was recruited in this study. CMA revealed that the fetus with TOF has a microdeletion on the 22q11.2 locus, and his mother was further confirmed a somatic mosaicism of 22q11.2 microdeletion by interphase FISH. Somatic mosaic 22q11.2 deletion in the mother was validated in the metaphase lymphocytes. Clinical examinations related to 22q11.2DS showed that the mother had hypocalcemia and low percentages of CD4 + T helper cells. The family history of recurrent fetal conotruncal defects and genetic results demonstrated the inherited possibility of maternal germline mosaicism of the 22q11.2 microdeletion. CONCLUSION: Our report was the first case in a Chinese family to present that a somatic and suspected gonadal mosaicism of the 22q11.2 microdeletion in female causes recurrent fetal conotruncal defects.

Rare Copy Number Variations Might Not be Involved in the Molecular Pathogenesis of PA-IVS in an Unselected Chinese Cohort.

Congenital heart defect (CHD) is one of the most common birth defects in China, while pulmonary atresia with intact ventricular septum (PA-IVS) is the life-threatening form of CHD. Numerous previous studies revealed that rare copy number variants (CNVs) play important roles in CHD, but little is known about the prevalence and role of rare CNVs in PA-IVS. In this study, we conducted a genome-wide scanning of rare CNVs in an unselected cohort consisted of 54 Chinese patients with PA-IVS and 20 patients with pulmonary atresia with ventricular septal defect (PA-VSD). CNVs were identified in 6/20 PA-VSD patients (30%), and three of these CNVs (15%) were considered potentially pathogenic. Two pathogenic CNVs occurred at a known CHD locus (22q11.2) and one likely pathogenic deletion located at 13q12.12. However, no rare CNVs were detected in patients with PA-IVS. Potentially pathogenic CNVs were more enriched in PA-VSD patients than in PA-IVS patients (p = 0.018). No rare CNVs were detected in patients with PA-IVS in our study. PA/IVS might be different from PA/VSD in terms of genetics as well as anatomy.

22q11.2 Deletion Status and Perioperative Outcomes for Tetralogy of Fallot with Pulmonary Atresia and Multiple Aortopulmonary Collateral Vessels.

Deletion of 22q11.2 (del22q11) is associated with adverse outcomes in patients with tetralogy of Fallot (TOF). We sought to investigate its contribution to perioperative outcome in patients with a severe form of TOF characterized by pulmonary atresia (PA) or severe pulmonary stenosis (PS) and major aortopulmonary collateral arteries (MAPCAS). We conducted a retrospective review of patients with TOF/MAPCAS who underwent staged surgical reconstruction between 1995 and 2006. Groups were compared according to 22q11.2 deletion status using t-tests or the Wilcoxon Rank sum test. We included 26 subjects, 24 of whom survived the initial operation. Of those, 21 subjects had known deletion status and constitute the group for this analysis [15 with no deletion present (ND) and 6 del22q11 subjects]. There was no difference with respect to occurrence of palliative procedure prior to initial operation, or to timing of closure of the ventricular septal defect (VSD). Other than higher prevalence of prematurity (50%) in the del22q11 group versus no prematurity in the ND, the groups were comparable in terms of pre-operative characteristics. The intra- and post-operative course outcomes (length of cardiopulmonary bypass, use of vasopressors, duration of intensive care and length of hospital stay, tube-feeding) were also comparable. Although the del22q11 had longer mechanical ventilation than the ND, this difference was not significant [68 h (range 4-251) vs. 45 h (range 3-1005), p = 0.81]. In this detailed comparison of a small patient cohort, 22q11.2 deletion syndrome was not associated with adverse perioperative outcomes in patients with TOF, PA, and MAPCAS when compared to those without 22q11.2 deletion syndrome. These results are relevant to prenatal and neonatal pre-operative counseling and planning.

Chromosome 22q11 deletion in a patient with pulmonary atresia, intact ventricular septum, and confluent branch pulmonary arteries.

In this study, we report a patient with pulmonary atresia with intact ventricular septum (PA/IVS), confluent pulmonary arteries supplied by an arterial duct, and chromosome 22q11.2 microdeletion. The 22q11.2 deletion syndrome has been associated with anomalies of the outflow tracts, such as tetralogy of Fallot with either pulmonary stenosis or atresia, but we are aware of a solitary case described with pulmonary atresia when the ventricular septum is intact. The presence of genetic malformations can have long-term co-morbidities. By describing our patient, we aim to create awareness of this rare association.

Advances in molecular genetics for pulmonary atresia.

Genetic and environmental factors may be similar in certain CHD. It has been widely accepted that it is the cumulative effect of these risk factors that results in disease. Pulmonary atresia is a rare type of complex cyanotic CHD with a poor prognosis. Understanding the molecular mechanism of pulmonary atresia is essential for future diagnosis, prevention, and therapeutic approaches. In this article, we reviewed several related copy number variants and related genetic mutations, which were identified in patients with pulmonary atresia, including pulmonary atresia with ventricular septal defect and pulmonary atresia with intact ventricular septum.

Chromosome 22q11.21 microduplication in association with hypoplastic left heart syndrome with hypoplastic pulmonary arteries.

We describe a case of a baby girl born with hypoplastic left heart syndrome consisting of mitral atresia, aortic atresia, hypoplastic ascending aorta, and left ventricle. The pulmonary arteries were hypoplastic, measuring 3 mm. Fluorescence in situ hybridisation analysis demonstrated a microduplication of chromosome 22q11.2. Subsequent array comparative genomic hybridisation showed a gain of 2.3 Mb in one copy of chromosome 22q at band 22q11.21. The proband underwent a successful Norwood procedure with Sano shunt and subsequently underwent bi-directional Glenn shunt and Fontan procedure. This report highlights the association between hypoplastic left heart syndrome with hypoplastic pulmonary arteries and chromosome 22q11.21 microduplication.

Rare de novo copy number variants in patients with congenital pulmonary atresia.

BACKGROUND: Ongoing studies using genomic microarrays and next-generation sequencing have demonstrated that the genetic contributions to cardiovascular diseases have been significantly ignored in the past. The aim of this study was to identify rare copy number variants in individuals with congenital pulmonary atresia (PA). METHODS AND RESULTS: Based on the hypothesis that rare structural variants encompassing key genes play an important role in heart development in PA patients, we performed high-resolution genome-wide microarrays for copy number variations (CNVs) in 82 PA patient-parent trios and 189 controls with an Illumina SNP array platform. CNVs were identified in 17/82 patients (20.7%), and eight of these CNVs (9.8%) are considered potentially pathogenic. Five de novo CNVs occurred at two known congenital heart disease (CHD) loci (16p13.1 and 22q11.2). Two de novo CNVs that may affect folate and vitamin B12 metabolism were identified for the first time. A de novo 1-Mb deletion at 17p13.2 may represent a rare genomic disorder that involves mild intellectual disability and associated facial features. CONCLUSIONS: Rare CNVs contribute to the pathogenesis of PA (9.8%), suggesting that the causes of PA are heterogeneous and pleiotropic. Together with previous data from animal models, our results might help identify a link between CHD and folate-mediated one-carbon metabolism (FOCM). With the accumulation of high-resolution SNP array data, these previously undescribed rare CNVs may help reveal critical gene(s) in CHD and may provide novel insights about CHD pathogenesis.

A variant in the carboxyl-terminus of connexin 40 alters GAP junctions and increases risk for tetralogy of Fallot.

GJA5 gene (MIM no. 121013), localized at 1q21.1, encodes for the cardiac gap junction protein connexin 40. In humans, copy number variants of chromosome 1q21.1 have been associated with variable phenotypes comprising congenital heart disease (CHD), including isolated TOF. In mice, the deletion of Gja5 can cause a variety of complex CHDs, in particular of the cardiac outflow tract, corresponding to TOF in many cases. In the present study, we screened for mutations in the GJA5 gene 178 unrelated probands with isolated TOF. A heterozygous nucleotide change (c.793C>T) in exon 2 of the gene leading to the p.Pro265Ser variant at the carboxyl-terminus of the protein was found in two unrelated sporadic patients, one with classic anatomy and one with pulmonary atresia. This GJA5 missense substitution was not observed in 1568 ethnically-matched control chromosomes. Immunofluorescent staining and confocal microscopy revealed that cells expressing the mutant protein form sparse or no visible gap-junction plaques in the region of cell-cell contact. Moreover, analysis of the transfer of the gap junction permanent tracer lucifer yellow showed that cells expressing the mutant protein have a reduced rate of dye transfer compared with wild-type cells. Finally, use of a zebrafish model revealed that microinjection of the GJA5-p.Pro265Ser mutant disrupts overall morphology of the heart tube in the 37% (22/60) of embryos, compared with the 6% (4/66) of the GJA5 wild-type-injected embryos. These findings implicate GJA5 gene as a novel susceptibility gene for TOF.

Rare copy number variations in adults with tetralogy of Fallot implicate novel risk gene pathways.

Structural genetic changes, especially copy number variants (CNVs), represent a major source of genetic variation contributing to human disease. Tetralogy of Fallot (TOF) is the most common form of cyanotic congenital heart disease, but to date little is known about the role of CNVs in the etiology of TOF. Using high-resolution genome-wide microarrays and stringent calling methods, we investigated rare CNVs in a prospectively recruited cohort of 433 unrelated adults with TOF and/or pulmonary atresia at a single centre. We excluded those with recognized syndromes, including 22q11.2 deletion syndrome. We identified candidate genes for TOF based on converging evidence between rare CNVs that overlapped the same gene in unrelated individuals and from pathway analyses comparing rare CNVs in TOF cases to those in epidemiologic controls. Even after excluding the 53 (10.7%) subjects with 22q11.2 deletions, we found that adults with TOF had a greater burden of large rare genic CNVs compared to controls (8.82% vs. 4.33%, p = 0.0117). Six loci showed evidence for recurrence in TOF or related congenital heart disease, including typical 1q21.1 duplications in four (1.18%) of 340 Caucasian probands. The rare CNVs implicated novel candidate genes of interest for TOF, including PLXNA2, a gene involved in semaphorin signaling. Independent pathway analyses highlighted developmental processes as potential contributors to the pathogenesis of TOF. These results indicate that individually rare CNVs are collectively significant contributors to the genetic burden of TOF. Further, the data provide new evidence for dosage sensitive genes in PLXNA2-semaphorin signaling and related developmental processes in human cardiovascular development, consistent with previous animal models.

Genetic syndromes and outcome after surgical repair of pulmonary atresia and ventricular septal defect.

BACKGROUND: Genetic syndromes, especially 22q11 deletion (del22q11) syndrome, are common in patients with pulmonary atresia and ventricular septal defect (PA-VSD), but their association with long-term outcomes varies. The purpose of this study was to evaluate the long-term outcome after complete repair of PA-VSD and to determine the impact of genetic syndromes. METHODS: We reviewed our experience of 125 patients with PA-VSD who received primary or staged repair between 1978 and 2010. Evaluations for genetic syndromes included clinical features, cytogenetic analysis, and fluorescence in situ hybridization or multiplex ligation-dependent probe amplification. RESULTS: Genetic syndromes were documented in 26 patients (20.8%), including del22q11 in 16 patients, trisomy 21 in 2 patients, and other syndromes in 8 patients. The prevalence of hypoplastic pulmonary arteries was not significantly different between the syndromic and nonsyndromic groups. After 1,069 patient-years of follow-up, 20-year survival was 90% ± 6% in patients without syndromes and 14% ± 23% in patients with syndromes (p < 0.01). Multivariate analysis identified the presence of a genetic syndrome as an important risk factor for hospital and late mortality. Subgroup analysis showed that genetic syndromes other than del22q11 were associated with worse outcome. The rate of 10-year freedom from cardiac reintervention after repair was 53% ± 11%, with hypoplastic pulmonary arteries before repair as a major risk factor (p = 0.02). CONCLUSIONS: Genetic syndromes significantly affect survival after repair of PA-VSD, whereas genetic syndromes do not represent additional risk for reintervention. Repair is feasible in patients with syndromes, but suboptimal long-term outcome should be addressed when counseling parents.

Prenatally diagnosed case of 22q11.2 deletion syndrome associated with pulmonary artery aneurysm.

Here, we report a new case with chromosome 22q11 deletion and cardiac anomaly diagnosed prenatally by echocardiography. Fluorescence in situ hybridization (FISH) analysis demonstrated a heterozygous deletion at 22q11.2. Echocardiography revealed ventricular septal defect, pulmonary atresia, and aneurysm of the main pulmonary artery and its branches. Pulmonary artery aneurysm (PAA) is rarely seen in patients with 22q11.2 deletion syndrome (22qDS). In this case, PAA was found by prenatal echocardiographic examination at the 25th week of gestation. To date, no prenatally diagnosed case of 22qDS with PAA has been reported. This is the first 22qDS case with PAA that was detected prenatally by FISH analysis.

Determinants of outcome after surgical treatment of pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries.

OBJECTIVES: Identification of variables influencing surgical outcome in patients treated for pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries. METHODS: A total of 90 consecutive patients (median age, 12 months; range, 20 days to 35 years), who had primarily undergone either 1-stage unifocalization (n = 69) or palliation to promote native pulmonary arterial development (n = 21), were studied. Chromosome 22q11 deletion had occurred in 37% of the cases. Ventricular septal defect closure was accomplished in 70 patients (78%), with a mean postoperative right/left ventricular pressure ratio of 0.48 ± 0.14. RESULTS: The rate of 14-year survival, freedom from conduit reintervention, and freedom from percutaneous intervention on the pulmonary arteries was 75%, 46%, and 52%, respectively. At a median interval of 95 months (range, 1.5-164 months), the right/left ventricular pressure ratio did not differ significantly from early postoperatively. Univariate analysis showed that an absence of confluent intrapericardial pulmonary arteries favorably affected the postoperative right/left ventricular pressure ratio after ventricular septal defect closure (P = .04). Kaplan-Meier estimates showed age of 30 days or younger (P = .0004) and weight of 3 kg or less (P = .0004) at unifocalization and chromosome 22q11 deletion (P = .001) significantly affected survival. Chromosome 22q11 deletion was significantly associated with mortality, even in the Cox regression model (hazard ratio, 8.26; P = .003). Finally, ventricular septal defect closure during single-stage and single/multiple-stage procedures significantly correlated with both early (P = .0013 and P < .00001, respectively) and overall (P = .013 and P = .0007, respectively) survival. CONCLUSIONS: The results of surgery were satisfactory and durable, despite the need for repeated percutaneous or surgical reinterventions. The outcomes were negatively affected by neonatal age and low body weight and positively affected by simultaneous or staged ventricular septal defect closure. Finally, chromosome 22q11 deletion remained an independent variable affecting survival.

Neonatal Marfan syndrome: unusually large deletion of exons 24-26 of FBN1 associated with poor prognosis.

Neonatal Marfan syndrome is a very rare subset of the classical Marfan syndrome with pronounced phenotypic expression especially of the cardiovascular manifestations. It is associated with a very poor prognosis, with approximately 50% of affected infants dying from cardiac failure during the first year of life. We present a newborn with the classical phenotype of neonatal Marfan syndrome. Within few hours after birth, progressive and refractory heart failure developed. Postmortal molecular study revealed an unusually large deletion of exons 24-26 within the so-called neonatal region of the gene FBN1, which might explain the unfavourable course of the disease in our patient.

22q11.2 Deletion Syndrome is under-recognised in adult patients with tetralogy of Fallot and pulmonary atresia.

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.