[Show abstract][Hide abstract] ABSTRACT: Background Familial dilated cardiomyopathy (DCM) is genetically heterogeneous. Mutations in more than 40 genes have been identified in familial cases, mostly inherited in an autosomal dominant pattern. DCM due to recessive mutations is rarely observed. In consanguineous families, homozygosity mapping and whole exome sequencing (WES) can be utilized to identify the genetic defects in recessively inherited DCM. Methods In a consanguineous family with four affected siblings with severe DCM, we combined homozygosity mapping, linkage analysis and WES, to uncover the genetic defect. Results A region of homozygosity (ROH) on chromosome 8q24.13–24.23 was found to be shared by all of the four affected siblings. WES detected ~47,000 variants that were filtered to a homozygous mutation (p.Gly243Arg) in the FBXO32 gene, located within the identified ROH. The mutation segregated with the phenotype, replaced a highly-conserved amino acid, and was not detected in 1986 ethnically-matched chromosomes. FBXO32, which encodes a muscle-specific ubiquitin ligase, has been implicated in the pathogenesis of cardiomyopathy through the ubiquitin proteasome system (UPS). In addition, FBXO32-knockout mice manifest with cardiomyopathy. Screening the index patient for all of the WES variants in 48 genes known to be implicated in hypertrophic and dilated cardiomyopathy was negative. Conclusions Our data suggest that FBXO32 is a candidate gene for recessive DCM. Acting as a cardiac ubiquitin ligase, mutated FBXO32 could perturb the degradation of target proteins in the UPS, the impairment of which has been observed in cardiomyopathy. Our work proposes that genes encoding other ubiquitin ligases could also be implicated in familial cardiomyopathy.
Preview · Article · Dec 2016 · BMC Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: Aim:
To determine if a transthoracic echocardiography (TTE) can be used as the sole diagnostic imaging modality to evaluate children with congenital heart disease (CHD) undergoing cardiac surgery.
A retrospective study was carried out at the King Abdulaziz Cardiac Center. We reviewed all pediatric patients who underwent cardiac surgery during the period January 2011 to December 2011.
Three hundred ninety-one pediatric patients with CHD fulfilled the inclusion criteria. Of these patients, 287 (73%) underwent surgical interventions based on a TTE alone, while 105 (27%) required additional diagnostic imaging modalities, including a cardiac catheterization (68/105; 65%), cardiac computed tomography angiography (36/105; 35%), or cardiac magnetic resonance imaging (1/105; 1%). A TTE was not enough for all the patients who underwent a cardiac catheterization to find out additional anatomical information (22%), either to directly measure pulmonary artery pressures (62%) or to study vascular reactivity in patients with pulmonary hypertension (16%). Of 36 patients who underwent a cardiac computed tomography angiography, five (14%) had additional information to be added to TTE findings. Of all the patients, 81% had enough information using only the TTE compared to 19% in whom the TTE was not enough to provide all needed information. Only seven of 392 (0.02%) patients had additional minor intraoperative findings that did not affect the surgical decision.
Despite the emergence of other imaging modalities, a TTE can be used as the sole diagnostic imaging modality for a preoperative assessment in the majority of children with CHD. Other imaging modalities can be employed with limited indications.
No preview · Article · Nov 2015 · Congenital Heart Disease
[Show abstract][Hide abstract] ABSTRACT: Left ventricular (LV) dysfunction is a known complication after patent ductus arteriosus (PDA) occlusion. However, only limited studies with small number of patients and shorter duration of follow up were published. The study objective is to evaluate the effect of PDA occlusion on LV systolic function (LV-SFx).
Preview · Article · Oct 2015 · Journal of the Saudi Heart Association
[Show abstract][Hide abstract] ABSTRACT: Background Truncus arteriosus (TA) is characterised by failure of septation of the outflow tract into aortic and pulmonary trunks and is associated with high morbidity and mortality. Although ranked among the least common congenital heart defects, TA provides an excellent model for the role of individual genes in cardiac morphogenesis as exemplified by TBX1 deficiency caused by point mutations or, more commonly, hemizygosity as part of the 22q11.2 deletion syndrome. The latter genetic lesion, however, is only observed in a proportion of patients with TA, which suggests the presence of additional disease genes.
Objective To identify novel genes that cause Mendelian forms of TA.
Methods and results We exploited the occurrence of monogenic forms of TA in the Saudi population, which is characterised by high consanguinity, a feature conducive to the occurrence of Mendelian phenocopies of complex phenotypes as we and others have shown. Indeed, we demonstrate in two multiplex consanguineous families that we are able to map TA to regions of autozygosity in which whole-exome sequencing revealed homozygous truncating mutations in PRKD1 (encoding a kinase derepressor of MAF2) and NRP1 (encoding a coreceptor of vascular endothelial growth factor (VEGFA)). Previous work has demonstrated that Prkd1−/− is embryonic lethal and that its tissue-specific deletion results in abnormal heart remodelling, whereas Nrp1−/− develops TA. Surprisingly, molecular karyotyping to exclude 22q11.2 deletion syndrome in the replication cohort of 17 simplex TA cases revealed a de novo hemizygous deletion that encompasses PRDM1, deficiency of which also results in TA phenotype in mouse.
Conclusions Our results expand the repertoire of molecular lesions in chromatin remodelling and transcription factors that are implicated in the pathogenesis of congenital heart disease in humans and attest to the power of monogenic forms of congenital heart diseases as a complementary approach to dissect the genetics of these complex phenotypes.
Full-text · Article · Feb 2015 · Journal of Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: The pediatric cardiology division at the King Abdulaziz Cardiac center is a unit that provides a tertiary level of care for children with complex congenital and acquired heart diseases from all around Saudi Arabia. Further, we are also involved in training and research programs, both at national and international levels. This paper describes the organization and metrics of our section as well as our teaching and research activities. Besides our Pediatric Cardiology Fellowship Program, the following additional topics are outlined in detail: outpatient services, echocardiography, advanced cardiac imaging, cardiac catheterization, pediatric electrophysiology, pulmonary hypertension program, data collection, and academic activities.
Full-text · Article · Nov 2014 · European Heart Journal Supplements
[Show abstract][Hide abstract] ABSTRACT: The arterial switch operation (ASO) is the procedure of choice today for simple transposition of great arteries. This procedure results in anatomical correction of the defect and long-term complications are infrequent. We present what may be the first report of multiple aortic aneurysms in a 6-week-old baby boy 4 weeks post-ASO. Initial diagnosis was made by transthoracic echocardiography, which was confirmed by computed tomographic angiography and surgical inspection. The aneurysms were repaired surgically with two aortic homograft patches without complications.
Full-text · Article · Nov 2014 · European Heart Journal Supplements
[Show abstract][Hide abstract] ABSTRACT: The aim of the study is to describe varieties of congenital heart disease (CHD) in different types of conjoined twins (ConTw). This is a retrospective (from 1997 to 2014) analysis of 42 sets of ConTw with different levels of body and/or organ fusion, referred to our center for cardiac evaluation prior to separation. Conjoined twins were classified into Classes 1, 2, and 3 according to heart abnormalities and further subclasses of a, b, and c according to minor or major heart disease. Of the 42 sets, there were 35 sets of twins (83.3%) who were symmetrical including 3 craniopagus, 3 pygopagus, 14 thoracopagus, 11 omphalopagus, 3 ischiopagus, and 1 parapagus. Seven sets of twins (16.7%) were asymmetrical with a variable degree of thoraco-omphalo-ischiopagus fusion. Twenty-six of 40 sets (65%) were female. Overall incidence rate of cardiac abnormalities was 76.2%. Major cardiac abnormalities were common in thoracopagus twins (14 sets). Two sets (14%) shared the pericardium, whereas three sets (21.5%) were fused at atrial level, two sets (14%) at ventricle level, and seven sets (50%) had a severely malformed single heart with fusion at both the atrial and ventricular level. Conjoined twins have a high incidence of CHD. All symmetrical thoracopagus tetrapus twins had major cardiac abnormalities precluding their separation and all of them did not survive. Incidence of major cardiac malformations was less in the other types of ConTw.
Full-text · Article · Nov 2014 · European Heart Journal Supplements
[Show abstract][Hide abstract] ABSTRACT: Anomalies of systemic venous return are extremely heterogeneous congenital malformations with variable ranges from completely normal physiology to severe forms of right to left shunting requiring surgical treatment. Anomalous drainage of a right-sided superior vena cava (SVC) to the left atrium (LA) is one of the rarest variants of systemic venous return anomalies, characterized by right-to-left shunt physiology and cyanosis. Here we report a 2 years old girl presented with cyanosis which was observed shortly after birth by her parents but not further investigated. She is otherwise active girl and with normal growth and development. Her clinical examination was unremarkable apart from mild clubbing of the fingers and low oxygen saturation of 88-90% in room air. Her ECG and chest X-ray were unremarkable. Echocardiography showed bilateral SVC connected by a small innominate vein. The right SVC drains directly into the LA while the left SVC drains into the right atrium (RA) via a dilated coronary sinus. There is a small superior sinus venosus type atrial septum defect (ASD) with left to right shunt. Also, there is partial anomalous pulmonary venous return with right upper and right middle pulmonary veins draining directly into the right SVC, which is connected to LA. The right lower pulmonary vein and left pulmonary veins drain directly to LA. The rest of her echocardiography demonstrated normal heart structures and function. This patient was referred for surgical correction, including baffling of the right SVC to the RA and closure of the ASD. We describe this case to highlight the importance of recognizing this rare anomalous systemic venous connection as one of the very rare causes of cyanosis in the pediatric age group as well as at older age.
Full-text · Article · Oct 2014 · Journal of the Saudi Heart Association
[Show abstract][Hide abstract] ABSTRACT: A 9.5 months old boy with Down syndrome, weighing 4.8 kilograms, presented with history of failure to thrive. Clinically, he had symptoms and signs of congestive heart failure. His echocardiogram showed a large perimembranous ventricular septal defect (pmVSD) with some inlet extension covered by a large aneurysmal tissue with multiple right ventricular (RV) exits. Additionally, he had hypothyroidism and Hirschsprung disease. Instead of closing the VSD surgically, the VSD was successfully closed utilizing a 8 X 6 duct occluder. The baby stayed in the intensive care unit for one night. The next day after the procedure, the infant was stable and showed clinical improvement. Electrocardiogram (ECG) showed normal sinus rhythm with no evidence of heart block. Echocardiography 24 hours later, showed the device was in an excellent position, with a small residual leak. There was normal tricuspid valve inflow and normal aortic valve outflow with no significant valvar insufficiency. The baby was discharged home after 3 days in stable condition. We believe infants with such co-morbidities, which might complicate their post-operative course and prolong the intensive care unit admission, might benefit from such alternative management.
Full-text · Article · Apr 2014 · Journal of the Saudi Heart Association
[Show abstract][Hide abstract] ABSTRACT: Chronic kidney disease (CKD) is known to cause increased arterial stiffness, which is an important independent risk factor for adverse cardiovascular events. The purpose of this study was to assess the vascular properties of the aorta (AO) in a group of children with CKD using a noninvasive echocardiography (echo)-Doppler method. We studied 24 children with stages 2 through 5 CKD and 48 age-matched controls. Detailed echocardiographic assessment and echo-Doppler pulse wave velocity (PWV) was performed. Indices of arterial stiffness, including characteristic (Zc) and input (Zi) impedances, elastic pressure-strain modulus (Ep), and arterial wall stiffness index, were calculated. CKD patients underwent full nephrology assessment, and an iohexol glomerular filtration rate was performed, which allowed for accurate assignment of the CKD stage. CKD patients had greater median systolic blood pressure (114 vs. 110 mmHg; p < 0.04) and pulse pressure (51 vs. 40 mmHg; p < 0.001) compared with controls. PWV was similar between groups (358 vs. 344 cm s(-1); p = 0.759), whereas Zi (182 vs. 131 dyne s cm(-5); p < 0.001), Zc (146 vs. 138 dyne s cm(-5); p = 0.05), and Ep (280 vs. 230 mmHg; p < 0.02) were significantly greater in CKD than in controls. Although load-dependent measures of arterial stiffness were greater in non-dialysis dependent CKD patients, PWV was not increased compared with controls. This suggests that the increased arterial stiffness may not be permanent in these pediatric patients with kidney disease.
No preview · Article · Feb 2013 · Pediatric Cardiology
[Show abstract][Hide abstract] ABSTRACT: AimsThe contribution of the systolic function of the right ventricular (RV) outflow tract (RVOT) and of longitudinal shortening of the body of the right ventricle to global RV systolic function and exercise capacity in patients after tetralogy of Fallot (TOF) repair is unclear. Our aim was to characterize the functional role of the RVOT and to identify the most suitable method of assessing RV systolic function in clinical practice.Methods
The cardiac magnetic resonance (CMR) studies, echocardiograms, and medical records of 50 consecutive patients with repaired TOF who underwent CMR were reviewed. The volumes of the RVOT and of the remainder of the RV were measured separately. Echocardiographic RV strain measurements based on ultrasound speckle tracking were collected.ResultsAfter excluding the akinetic RVOT, RVEF was statistically higher (47.1 vs. 45.0%, P< 0.0001) but the average increase in EF was small. The correlations of fractional area change and global longitudinal strain, both by echocardiography, with global RVEF were moderate (r= 0.59, P= 0.0001 and r= 0.56, P= 0.0004, respectively). The correlation between RVEF and predicted maximal oxygen consumption (VO2max-predicted) was weak, regardless of whether the akinetic RVOT was included or not (r= 0.33, P= 0.049 and r= 0.36, P= 0.03, respectively). Of all imaging parameters, echocardiographic RV longitudinal strain correlated best with VO2max-predicted (r= 0.66, P= 0.0001).Conclusions
In patients following TOF repair, echocardiographic and CMR descriptors of global RV systolic function are, at best, weak predictors of exercise tolerance. Longitudinal function of the RV, measured remotely from the RVOT, may be a more important determinant of exercise performance than global RVEF in patients with aneurismal RVOTs.
[Show abstract][Hide abstract] ABSTRACT: Hereditary forms of cataract are genetically heterogeneous. Mutations in crystallin genes account for most Mendelian forms, but identification of other cataract genes has provided insights into additional molecular mechanisms that control lens transparency. In a multiplex consanguineous family with isolated congenital cataract, we identified a novel autosomal recessive cataract locus on 7q33-q36.1. Exome sequencing revealed a splice-site mutation in AGK, encoding acylglycerol kinase, which we confirm led to aberrant splicing and predicted premature truncation. This is the first mutation in this lipid metabolism gene to be implicated in the development of isolated cataract, although it remains to be seen if the mechanism involves perturbation of lenticular lipid composition or aberrant signaling during lens morphogenesis.
[Show abstract][Hide abstract] ABSTRACT: Right ventricular (RV) enlargement is used as a criterion for the treatment of RV outflow tract dysfunction in patients with congenital heart disease. Although RV volumes are most accurately measured by cardiac magnetic resonance (CMR), CMR is a limited resource. The aim of this study was to investigate whether simple echocardiographic measurements can adequately predict RV volumes below clinical thresholds, thereby reducing the need for CMR in some patients.
Children with repaired tetralogy of Fallot, double-outlet right ventricle, or truncus arteriosus who underwent CMR and echocardiography within a 4-week interval were retrospectively studied. From the four-chamber view, indexed RV lateral wall length, indexed RV end-diastolic perimeter length, and indexed RV end-diastolic area (RVEDAi), were measured. Results were compared with CMR indexed RV volume. The sensitivity and specifity of echocardiographic threshold values predicting RV volumes < 170 mL/m(2) were determined.
Fifty-one children (mean age, 12.7 ± 3.5 years; 25 male, 26 female) were reviewed. RVEDAi was correlated with CMR indexed RV volume (r = 0.60, P < .0001). Indexed RV end-diastolic perimeter length and indexed RV lateral wall length were not correlated with CMR. RVEDAi < 20 cm(2)/m(2) had 100% specificity to predict indexed RV volume ≤ 170 mL/m(2) (area under the curve, 0.79), reducing the need for CMR in 15 of 51 patients (29%). A threshold RVEDAi of 22 cm(2)/m(2) would reduce the need for CMR in 21 of 51 patients (41%) at the expense of one false-negative result. The coefficients of variation were 14.7% for intraobserver variability and 9.6% for interobserver variability.
The specificity of echocardiography-measured RVEDAi can be set to predict RV volumes below a 170 mL/m(2) threshold in 100% of cases. This may reduce the need for CMR to determine RV volumes in ≥25% of patients with congenital heart disease, potentially reducing patient burden and costs.
No preview · Article · Feb 2012 · Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography
[Show abstract][Hide abstract] ABSTRACT: Both primary pulmonary artery hypertension (PPAH) and autoimmune polyendocrine syndrome (APS) are rare disorders in children. We report a boy who was diagnosed with severe PPAH at 12 years of age. He was treated with prostacyclin for 6 years, briefly with adjunct bosentan, and eventually sildenafil was added. Six years later, after his diagnosis of PPAH, he developed APS in the form of hyperthyroidism and type 1 diabetes mellitus. No mutations were identified through genetic testing of bone morphogenetic protein receptor type II and the autoimmune-regulator gene. To our knowledge this is the first description of the combination of these two extremely rare diseases in a child.
No preview · Article · Aug 2010 · Pediatric Cardiology
[Show abstract][Hide abstract] ABSTRACT: We report a newborn male who was diagnosed with a double inlet left ventricle with pulmonary atresia antenatally. Postnatally, it was difficult to determine his arch anatomy echocardiographically. Therefore, he underwent three-dimensional computed tomography angiography, which confirmed the echocardiographic findings and demonstrated a bovine aortic arch. He additionally had a single coronary artery. To our knowledge, the association of a single ventricle with a single outlet of bovine morphology is novel.
No preview · Article · Aug 2009 · Congenital Heart Disease