Zeev Perles

Absent ductus venosus in the fetus: review of the literature and first report of direct umbilical venous drainage to the coronary sinus.

The ductus venosus connects the portal and umbilical veins with the inferior vena cava and acts as a sphincter to protect the fetus from placental overcirculation. Its absence usually causes hydrops fetalis and is associated with high mortality rate, chromosomal anomalies and congenital malformations. In this condition, the umbilical vein almost always drains directly into right-sided structures such as inferior vena cava or right atrium. We reviewed the literature and describe the first case of a fetus with absent ductus venosus and direct connection of the umbilical vein to the coronary sinus.

A human laterality disorder caused by a homozygous deleterious mutation in MMP21

Background Laterality in the vertebrate embryo is determined by left-right asymmetric gene expression driven by the flow of extraembryonic fluid across the embryonic node. Defects in these processes cause heterotaxy, the abnormal formation and arrangement of visceral organs that can range from complete inversion of symmetry to the selective misarrangement of organs. However, our understanding of the genetic causality for laterality defects in human beings remains relatively limited. Methods We performed whole exome sequencing in a consanguineous family with heterotaxia. To interrogate the pathogenic potential of the discovered variant, we used an in vivo system in which the potential of the candidate gene to induce L-R asymmetry was tested by transient suppression and CRISPR/Cas9-induced deletions. We also used in vitro assays to test a possible link between our exome-derived candidate and Notch signaling. Results We identified a homozygous 2 bp deletion in MMP21, encoding matrix metalloproteinase-21, as the sole coding mutation that segregated with the phenotype. Transient suppression or CRISPR/Cas9-mediated deletion of mmp21 in zebrafish embryos induced cardiac looping defects, with concomitant disruption of laterality markers in the lateral plate mesoderm and disrupted notch signalling in vitro and in vivo. Conclusions Our data implicate loss of MMP21 as a cause of heterotaxy in humans with concomitant defects in Notch signaling. In support of this finding, a homozygous missense mutation in MMP21 was identified previously in mice with N-Ethyl-N-Nitrosourea (ENU)-induced heterotaxy. Taken together, these observations suggest a role of matrix metalloproteinases in the establishment of asymmetric organ development, likely through the regulation of morphogenetic signals.

Conotruncal malformations and absent thymus due to a deleterious NKX2-6 mutation

Background Truncus arteriosus (TA) accounts for ∼1% of congenital heart defects. The aetiology of isolated TA is largely unknown but when occurring as part of a syndrome, it is mostly associated with chromosome 22q11 deletion. Vice versa, the most common congenital heart defects associated with chromosome 22q11 deletion are conotruncal malformations. In this study we investigated the cause of multiple conotruncal malformations accompanied by athymia in a consanguineous family. Methods and results Whole exome analysis revealed a homozygous deleterious mutation in the NKX2-6 gene. Conclusions NKX2-6 encodes a homeobox-containing protein which is expressed in mouse embryo at E8.0-E9.5 at the caudal pharyngeal arches and the outflow tract. A single missense mutation was previously implicated in the aetiology of familial isolated TA; however, null mice are entirely normal. The clear phenotype associated with a homozygous deleterious mutation in the present report, falls well within the spectrum of the cardiac defects seen in DiGeorge syndrome, is in agreement with NKX2-6 downstream location in the TBX1 signalling pathway and confirms NKX2-6 role in human cardiogenesis.

Intracardiac Echogenic Foci Have No Hemodynamic Significance in the Fetus

Intracardiac echogenic foci (ECFs), probably representing microcalcifications of the papillary muscles, are a common finding in fetal ultrasonic screening examinations. Their significance is unclear, and their value as markers for chromosomal anomalies is debatable. It also is unknown whether ECFs predict abnormal cardiac performance. This prospective study analyzed and compared the systolic and diastolic properties of the heart in 28 fetuses with ECFs and 70 fetuses without ECFs using both conventional and novel myocardial deformation methods. The findings suggest that left-sided ECFs do not predict depressed left- or right-side systolic or diastolic properties in the fetus. A longitudinal study that would follow ECF fetuses into their childhood is warranted to confirm the findings of this study.

Congenital valvular defects associated with deleterious mutations in the PLD1 gene

Background The underlying molecular aetiology of congenital heart defects is largely unknown. The aim of this study was to explore the genetic basis of non-syndromic severe congenital valve malformations in two unrelated families. Methods Whole-exome analysis was used to identify the mutations in five patients who suffered from severe valvular malformations involving the pulmonic, tricuspid and mitral valves. The significance of the findings was assessed by studying sporulation of yeast carrying a homologous Phospholipase D (PLD1) mutation, in situ hybridisation in chick embryo and echocardiography and histological examination of hearts of PLD1 knockout mice. Results Three mutations, p.His442Pro, p.Thr495fs32* and c.2882+2T>C, were identified in the PLD1 gene. The mutations affected highly conserved sites in the PLD1 protein and the p.His442Pro mutation produced a strong loss of function phenotype in yeast homologous mutant strain. Here we show that in chick embryos PLD1 expression is confined to the forming heart (E2–E8) and homogeneously expressed all over the heart during days E2–E3. Thereafter its expression decreases, remaining only adjacent to the atrioventricular valves and the right ventricular outflow tract. This pattern of expression follows the known dynamic patterning of apoptosis in the developing heart, consistent with the known role of PLD1 in the promotion of apoptosis. In hearts of PLD1 knockout mice, we detected marked tricuspid regurgitation, right atrial enlargement, and increased flow velocity, narrowing and thickened leaflets of the pulmonic valve. Conclusions The findings support a role for PLD1 in normal heart valvulogenesis.

Cardiac, Lung, and Brain Thrombosis in a Child with Obstructive Sleep Apnea

A 3‐year‐old boy with failure to thrive and severe adenotonsillar hypertrophy with a clinical presentation of prolonged obstructive sleep apnea (OSA), was referred to the emergency room due to severe respiratory distress and anasarca. Echocardiography revealed right heart failure, a cystic lesion in the right ventricle and severe pulmonary hypertension. D‐dimer was elevated but spiral computerized tomography (CT) and lung scan did not show any perfusion defects. Excision of the cardiac lesion during open‐heart surgery, lung biopsy, and adenotonsillectomy were performed. Pathological examination showed an intracadiac organized thrombus and eccentric intimal fibrosis of the pulmonary arteries—which is a pathognomonic of pulmonary arterial microemboli. Brain CT revealed vein thrombosis of the left sigmoid sinus. Blood tests for inherited thrombophilia were normal. Today, 5 years after adenotonsillectomy, the child is normally developed, completely asymptomatic, free of any medications, and has a normal echocardiography. This case report may indicate that prolonged OSA can be a procoagulant state which can cause severe cardiovascular morbidity in children. Pediatr. Pulmonol. 2010; 45:836–839.

Variable phenotypic presentation of a novel FOXF1 missense mutation in a single family.

Heterozygous mutations in the FOXF1 transcription factor gene are implicated in alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV), a developmental disorder of the lungs classically presenting with pulmonary hypertension and early demise. Evidence has suggested haploinsufficiency and partial paternal imprinting. We present a family with several affected members with an extremely variable phenotype.

Hepatopulmonary Syndrome in Patients With Cystic Fibrosis and Liver Disease

Hepatopulmonary syndrome (HPS) is a liver-induced lung disorder defined as a triad of liver disease, pulmonary vascular dilatation, and a defect in oxygenation. It can complicate chronic liver disease of any etiology, but is most commonly associated with portal hypertension. Severe liver disease with portal hypertension is present in 2% to 8% of patients with cystic fibrosis (CF), but to date, to our knowledge, only one patient with CF has been reported to suffer from HPS. Here, we describe two patients with CF diagnosed with HPS, one subsequent to unresolved hypoxemia and the other following screening for HPS performed in our center. We speculate that HPS is underdiagnosed in patients with CF because of their coexisting respiratory morbidity, and we advocate routine screening for every patient with CF who has liver disease and portal hypertension.

Mutations in PPCS, Encoding Phosphopantothenoylcysteine Synthetase, Cause Autosomal-Recessive Dilated Cardiomyopathy

Coenzyme A (CoA) is an essential metabolic cofactor used by around 4% of cellular enzymes. Its role is to carry and transfer acetyl and acyl groups to other molecules. Cells can synthesize CoA de novo from vitamin B5 (pantothenate) through five consecutive enzymatic steps. Phosphopantothenoylcysteine synthetase (PPCS) catalyzes the second step of the pathway during which phosphopantothenate reacts with ATP and cysteine to form phosphopantothenoylcysteine. Inborn errors of CoA biosynthesis have been implicated in neurodegeneration with brain iron accumulation (NBIA), a group of rare neurological disorders characterized by accumulation of iron in the basal ganglia and progressive neurodegeneration. Exome sequencing in five individuals from two unrelated families presenting with dilated cardiomyopathy revealed biallelic mutations in PPCS, linking CoA synthesis with a cardiac phenotype. Studies in yeast and fruit flies confirmed the pathogenicity of identified mutations. Biochemical analysis revealed a decrease in CoA levels in fibroblasts of all affected individuals. CoA biosynthesis can occur with pantethine as a source independent from PPCS, suggesting pantethine as targeted treatment for the affected individuals still alive.

Tetralogy of Fallot with Pulmonic Atresia with Cyclic Occlusion of an Associated Aortic Sinus of Valsalva–Pulmonary Artery Window

A first case of an unusual aortopulmonary window with tetralogy of Fallot associated with pulmonary atresia is presented. The aortopulmonary window was at the aortic sinus of Valsalva. The left aortic leaflet prevented pulmonary hypertension by occluding the window in systole.