Association of Myocardial Muscle Non-Compaction and Multiple Ventricular Septal Defects by Echocardiography.

The aim of this study is to examine the possible high association between multiple ventricular septal defect (mVSDs) and noncompaction cardiomyopathy (NCM) as same embryological origin, and the effect of depressed ventricular function in NCM cases during the follow-up, using echocardiography. A total of 150 patients with mVSDs were diagnosed in a single center in Saudi Arabia; 40 cases with isolated or associated with minor congenital heart disease were recruited. Three specialist echocardiography consultants confirmed the NCM diagnosis separately using Jenni, Chin and Patrick criteria, and myocardial function was estimated by ejection fraction at admission and at follow-up after surgery. Stata-14 to analyze the data was used. In our cohort of 40 cases with mVSD (median age at diagnosis = 0.5 years; mean follow-up = 4.84 years), 13(33%) had criteria of non-compaction confirmed by the three specialist consultants. All were operated by surgery and 11 hybrid approach (interventional & surgery). A significant relationship between abnormal trabeculations and mVSD with or without non-compaction was observed, 34% vs 66% respectively (p < 0.03, Fisher's exact test). A repeated-measures t-test found the difference between follow-up and preoperative ejection-fractions to be statistically significant (t (39) = 2.07, p < 0.04). Further, the myocardial function in the mVSD non-compaction group normalized substantially postoperatively compared with preoperative assessment (mean difference (MD) 11.77, 95% CI: 4.40-19.14), whilst the mVSD group with normal myocardium had no significant change in the myocardium function (MD 0.74, 95% CI: -4.10-5.58). Thus, treatment outcome appears better in the mVSD non-compaction group than their peers with normal myocardium. Acknowledging the lack of genetic data, it is evident the high incidence of non-compaction in this cohort of patients with mVSD and supports our hypothesis of embryonic/genetic link, unlikely to be explained by acquired cardiomyopathy.

Combining exome/genome sequencing with data repository analysis reveals novel gene-disease associations for a wide range of genetic disorders.

PURPOSE: Within this study, we aimed to discover novel gene-disease associations in patients with no genetic diagnosis after exome/genome sequencing (ES/GS). METHODS: We followed two approaches: (1) a patient-centered approach, which after routine diagnostic analysis systematically interrogates variants in genes not yet associated to human diseases; and (2) a gene variant centered approach. For the latter, we focused on de novo variants in patients that presented with neurodevelopmental delay (NDD) and/or intellectual disability (ID), which are the most common reasons for genetic testing referrals. Gene-disease association was assessed using our data repository that combines ES/GS data and Human Phenotype Ontology terms from over 33,000 patients. RESULTS: We propose six novel gene-disease associations based on 38 patients with variants in the BLOC1S1, IPO8, MMP15, PLK1, RAP1GDS1, and ZNF699 genes. Furthermore, our results support causality of 31 additional candidate genes that had little published evidence and no registered OMIM phenotype (56 patients). The phenotypes included syndromic/nonsyndromic NDD/ID, oral-facial-digital syndrome, cardiomyopathies, malformation syndrome, short stature, skeletal dysplasia, and ciliary dyskinesia. CONCLUSION: Our results demonstrate the value of data repositories which combine clinical and genetic data for discovering and confirming gene-disease associations. Genetic laboratories should be encouraged to pursue such analyses for the benefit of undiagnosed patients and their families.

Molecular Dynamics Simulation Reveals Exposed Residues in the Ligand-Binding Domain of the Low-Density Lipoprotein Receptor that Interacts with Vesicular Stomatitis Virus-G Envelope.

Familial hypercholesterolemia (FH) is an autosomal dominant disease most often caused by mutations in the low-density lipoprotein receptor (LDLR) gene, which consists of 18 exons spanning 45 kb and codes for a precursor protein of 860 amino acids. Mutations in the LDLR gene lead to a reduced hepatic clearance of LDL as well as a high risk of coronary artery disease (CAD) and sudden cardiac death (SCD). Recently, LDLR transgenes have generated interest as potential therapeutic agents. However, LDLR packaging using a lentiviral vector (LVV) system pseudotyped with a vesicular stomatitis virus (VSV)-G envelope is not efficient. In this study, we modified the LVV system to improve transduction efficiency and investigated the LDLR regions responsible for transduction inhibition. Transduction efficiency of 293T cells with a 5'-LDLReGFP-3' fusion construct was only 1.55% compared to 42.32% for the eGFP construct. Moreover, co-expression of LDLR affected eGFP packaging. To determine the specific region of the LDLR protein responsible for packaging inhibition, we designed constructs with mutations or sequential deletions at the 3' and 5' ends of LDLR cDNA. All constructs except one without the ligand-binding domain (LBD) (pWoLBD-eGFP) resulted in low transduction efficiency, despite successful packaging of viral RNA in the VSV envelope, as confirmed through RT-PCR. When we evaluated a direct interaction between LDLR and the VSV envelope glycoprotein using MD simulation and protein-protein interactions, we uncovered Val119, Thr120, Thr67, and Thr118 as exposed residues in the LDLR receptor that interact with the VSV protein. Together, our results suggest that the LBD of LDLR interacts with the VSV-G protein during viral packaging, which significantly reduces transduction efficiency.

The Phenotype and Outcome of Infantile Cardiomyopathy Caused by a Homozygous ELAC2 Mutation.

OBJECTIVE: Cardiomyopathy (CMP) in children is a clinically and genetically heterogeneous group of disorders. Disease-associated mutations have been identified in more than 50 genes. Recently, mutations in the mitochondrial tRNA processing gene, ELAC2, were reported to be associated with the recessively inherited form of hypertrophic CMP (HCM). This study is aimed at describing the cardiac phenotype and outcome of ELAC2 mutation. METHODS: We performed whole exome sequencing followed by targeted mutation screening to identify the genetic etiology of severe infantile-onset CMP in 64 consanguineous Saudi families. RESULTS: A previously reported mutation (p.Phe154Leu) in ELAC2 gene was detected in 16 families. The index cases presented between 2 and 7 months of age with HCM in 13 infants and dilated CMP (DCM) in 3. Pericardial effusion was observed in 7 infants (44%). All infants died with a median age of death of 4 months. Almost 1/3 of them died during the initial presentation. CONCLUSION: Our study suggests screening the ELAC2 gene in severe infantile-onset HCM or DCM of unknown etiology, especially in the presence of pericardial effusion. Our work demonstrates a universally poor outcome of the (p.Phe154Leu) variant in ELAC2 gene; a correlation that helps in counseling parents and in planning appropriate medical intervention.

Combined TSC1 and LMX1B mutations in a single patient.

Tuberous sclerosis complex (TSC) and nail-patella syndrome (NPS) are autosomal dominant pleiotropic disorders with full penetrance that can both involve kidneys. TSC1 and NPS genes are located on chromosome 9q3. In a large family with the two disorders with two novel frameshift TSC1 and LMX1B mutations, we describe the phenotypes. The father, who has both disorders, has passed on TSC to three of his children, NPS to another three, and both TSC and NPS to one child. Patients carrying both mutations appear to show an additive phenotype and no obvious epistatic effects. The segregation of two dominant disorders in this family poses a challenge for genetic counseling and indicates the importance of a careful clinical and molecular evaluation for accurate risk assessment.

Genomic analysis of primordial dwarfism reveals novel disease genes.

Primordial dwarfism (PD) is a disease in which severely impaired fetal growth persists throughout postnatal development and results in stunted adult size. The condition is highly heterogeneous clinically, but the use of certain phenotypic aspects such as head circumference and facial appearance has proven helpful in defining clinical subgroups. In this study, we present the results of clinical and genomic characterization of 16 new patients in whom a broad definition of PD was used (e.g., 3M syndrome was included). We report a novel PD syndrome with distinct facies in two unrelated patients, each with a different homozygous truncating mutation in CRIPT. Our analysis also reveals, in addition to mutations in known PD disease genes, the first instance of biallelic truncating BRCA2 mutation causing PD with normal bone marrow analysis. In addition, we have identified a novel locus for Seckel syndrome based on a consanguineous multiplex family and identified a homozygous truncating mutation in DNA2 as the likely cause. An additional novel PD disease candidate gene XRCC4 was identified by autozygome/exome analysis, and the knockout mouse phenotype is highly compatible with PD. Thus, we add a number of novel genes to the growing list of PD-linked genes, including one which we show to be linked to a novel PD syndrome with a distinct facial appearance. PD is extremely heterogeneous genetically and clinically, and genomic tools are often required to reach a molecular diagnosis.

Novel V97G ASAH1 mutation found in Farber disease patients: unique appearance of the disease with an intermediate severity, and marked early involvement of central and peripheral nervous system.

Farber disease is a rare inherited lysosomal storage disorder caused by ceramidase deficiency that leads to accumulation of ceramide in various tissues. Mutations within ASAH1 encoding for acid ceramidase are responsible for the disease. Here we report two siblings with Farber disease who carry a novel V97G with the parents and a sister being asymptomatic carriers. The mutation site was found to be highly conserved among different species using ClustalW2 alignment. Functional prediction tools indicated the mutation to be pathogenic. Electron microscopy based ultrastructural studies using skin biopsy showed inclusion of enlarged lysosomes and presence of the zebra bodies. The T1 weighted magnetic resonance images of the brain indicated diffuse loss of the deep white matter volume predominantly along the occipital horns of the lateral ventricle with subsequent facet dilatation of the supratentorial and infratentorial ventricular system. This is the first report of a detailed clinical and molecular analysis of cases with Farber disease from Saudi Arabia.

Further Delineation of the Phenotype of Congenital Disorder of Glycosylation DPAGT1-CDG (CDG-Ij) Identified by Homozygosity Mapping.

Congenital disorders of glycosylation (CDG) are an expanding group of genetic diseases affecting protein and lipid glycosylation. These disorders have a variable presentation and are individually rare. DPAGT1-CDG is a protein N-glycosylation disorder with epilepsy, development delay, severe hypotonia, and dysmorphy, reported in a single patient. Here we present the second family with DPAGT1-CDG identified through homozygosity mapping in a large consanguineous family with 18 affected infants. The patients had severe hypotonia, global developmental delay, seizures, and microcephaly but no dysmorphy. In the index case, the brain MRI revealed delayed myelination, and there was fiber type disproportion on muscle biopsy. Homozygosity mapping identified a large block of homozygosity on chromosome 11p15.5-q25 where two known CDG-I causing genes, ALG9 and DPAGT1, are located. Sequencing ALG9 did not reveal any mutations while analysis of DPAGT1 identified a novel homozygous mutation c.902G>A (p.R301H) in two affected infants. The disorder was fatal in all affected cases and mostly in early infancy.

Craniofacial anomalies, humero-radial synostosis, rhizomelic limb shortness: previously unrecognized autosomal recessive syndrome.

Humero-radial synostosis (HRS) is a rare skeletal anomaly that might be seen in some craniosynostosis syndromes, notably Antley-Bixler syndrome, and in other disorders in association with skeletal anomalies. Here we report on two daughters of first cousin Saudi parents with syndromic HRS. Both patients had distinctive craniofacial features including cranium bifidum occultum, hypertelorism, epicanthus inversus, capillary hemangiomata, and malformed ears. Musculoskeletal examination revealed rhizomelic shortness with normal hands and feet. Skeletal survey showed bilateral HRS with no evidence of craniosynostosis. The craniofacial manifestations in these two patients do not match any of the syndromes known to be associated with HRS. We consider that the constellation is unique and apparently represents a previously unrecognized syndrome.