Whole-exome sequencing revealed a likely pathogenic variant in NF1 causing neurofibromatosis type I and Arrhythmogenic Cardiomyopathy.

BACKGROUND: Neurofibromatosis type I (NF1) is a genetic disorder characterized by the tumor's development in nerve tissue. Complications of NF1 can include pigmented lesions, skin neurofibromas, and heart problems such as cardiomyopathy. In this study, we performed whole-exome sequencing (WES) on an Iranian patient with NF1 to identify the genetic cause of the disease. METHODS: Following clinical assessment, WES was used to identify genetic variants in a family with a son suffering from NF1. No symptomatic manifestations were observed in other family members. In the studied family, in silico and segregation analysis were applied to survey candidate variants. RESULTS: Clinical manifestations were consistent with arrhythmogenic cardiomyopathy (ACM). WES detected a likely pathogenic heterozygous missense variant, c.3277G > A:p.Val1093Met, in the NF1 gene, confirmed by PCR and Sanger sequencing. The patient's parents and brother had a normal sequence at this locus. CONCLUSIONS: Although there is no cure for NF1, genetic tests, such as WES, can detect at-risk asymptomatic family members. Furthermore, cardiac evaluation could also help these patients before heart disease development.

Whole-exome sequencing uncovers a novel EFEMP2 gene variant (c.C247T) associated with dominant nonsyndromic thoracic aortic aneurysm.

BACKGROUND: Thoracic aortic aneurysm (TAA) is a multifactorial disorder. Familial TAA, which is more clinically aggressive, is associated with a high risk of lethal dissection or rupture. Genetic evaluation can provide TAA patients with personalized treatment and help in predicting risk to family members. OBJECTIVE: The purpose of this investigation was to report a likely pathogenic variant in the EFEMP2 gene that may contribute to TAA in a family with a documented history of the condition. METHODS: In the index patient, the causative genetic predisposition was identified using whole-exome sequencing. The potential likely pathogenic effect of the candidate variant was further analyzed through bioinformatics analysis, homology modeling, and molecular docking. RESULTS: The results revealed a likely pathogenic heterozygous variant, c.247C>T p.Arg83Cys, in exon 4 of the EFEMP2 gene (NM_016938), which was predicted to have disease-causing effects by MutationTaster, PROVEAN, SIFT, and CADD (phred score = 27.6). CONCLUSION: In this study, a likely pathogenic variant in the EFEMP2 gene was identified in an Iranian family with a dominant pattern of autosomal inheritance of TAA. This finding underscores the importance of conducting molecular genetic evaluations in families with nonsyndromic TAA and the significance of early detection of at-risk family members.

Polymorphism of rs599839 in the PSRC1 gene is associated with coronary artery disease in an Iranian population.

Introduction: Coronary artery disease (CAD) is the leading health complication worldwide because of its high prevalence and mortality. The association between CAD susceptibility and the rs599839 (C/T) polymorphism in the human proline and serine-rich coiled-coil (PSRC1) was reported in a genome-wide association study. To validate this association, we performed this case-control study to genotype the 1p13.3 (rs599839) locus in a sample of the Iranian population with CAD (stenosis≥70% in≥1 coronary artery). Methods: We performed an association analysis with PCR and Sanger sequencing of rs599839 (C/T) polymorphism and CAD risk in 280 CAD patients and 287 healthy controls defined as a coronary calcium score of zero and no noncalcified plaques in coronary computed tomography angiography. SPSS, version 16.0, was applied for statistical analysis. Results: The rs599839 (C/T) locus showed a significant association with CAD (P value<0.001). TT and CT genotypes were associated with CAD (P value<0.001). Furthermore, the dominant status (TT+CT vs. CC) was associated with an increased risk of CAD (OR, 9.14; 95% CI, 3.77 to 22.15; and P value<0.001). Conclusion: The study findings indicate strong evidence for rs599839 (C/T) association with CAD risk.

Arrhythmogenic left ventricular cardiomyopathy caused by a novel likely pathogenic DSP mutation, p.K1165Rfs*8, in a family with sudden cardiac death.

OBJECTIVE: We conducted an investigation into the clinical and molecular characteristics of Arrhythmogenic left ventricular cardiomyopathy (ALVC) caused by a novel likely pathogenic mutation in an Iranian pedigree with sudden cardiac death (SCD). BACKGROUND: ALVC is a genetically inherited myocardial disease characterized by the substitution of fibro-fatty tissue in the left ventricular myocardium, predominantly inherited in an autosomal dominant pattern and is commonly associated with genes involved in encoding desmosomal proteins, specifically Desmoplakin (DSP). METHODS: The patient and available family members underwent a comprehensive clinical assessment, including Cardiac magnetic resonance (CMR) imaging, along with Whole-exome sequencing (WES). The identified variant was confirmed and segregated by Polymerase chain reaction (PCR) and Sanger sequencing in the family members. RESULTS: A novel likely pathogenic heterozygous variant, DSP (NM_004415.4), c.3492_3498del, p.K1165Rfs*8 was discovered in the proband. This variant is likely to be the primary reason for ALVC in this specific family. This variant was confirmed by Sanger sequencing and segregated in other affected members of the family. CONCLUSION: We identified a novel likely pathogenic variant in the DSP gene, which has been identified as the cause of ALVC in an Iranian family. Our investigation underscores the importance of genetic testing, specifically WES, for individuals suspected of ALVC and have a family history of SCD.

A novel heterozygous missense MYH7 mutation potentially causes an autosomal dominant form of myosin storage myopathy with dilated cardiomyopathy.

BACKGROUND: The MYH7 gene, which encodes the slow/ß-cardiac myosin heavy chain, is mutated in myosin storage myopathy (MSM). The clinical spectrum of MSM is quite heterogeneous in that it ranges from cardiomyopathies to skeletal myopathies or a combination of both, depending on the affected region. In this study, we performed clinical and molecular examinations of the proband of an Iranian family with MSM in an autosomal dominant condition exhibiting proximal muscle weakness and dilated cardiomyopathy. METHODS: Following thorough clinical and paraclinical examinations, whole-exome sequencing `was performed on the proband (II-5). Pathogenicity prediction of the candidate variant was performed through in-silico analysis. Co-segregation analysis of the WES data among the family members was carried out by PCR-based Sanger sequencing. RESULTS: A novel heterozygous missense variant, MYH7 (NM_000257): c.C1888A: p.Pro630Thr, was found in the DNA of the proband and his children and confirmed by Sanger sequencing. The in-silico analysis revealed that p.Pro630Thr substitution was deleterious. The novel sequence variant fell within a highly conserved region of the head domain. Our findings expand the spectrum of MYH7 mutations. CONCLUSIONS: This finding could improve genetic counseling and prenatal diagnosis in families with clinical manifestations associated with MYH7-related myopathy.

Identification of a novel pathogenic variant in KCNH2 in an Iranian family with long QT syndrome 2 by whole-exome sequencing.

Background: Long QT syndrome (LQTS) is a lethal cardiac condition. However, the clinical implementation of genetic testing has now made LQTS eminently treatable. Next-generation sequencing has remarkable potential for both clinical diagnostics and research of LQTS. Here, we investigated the genetic etiology in an LQTS-suspected Iranian pedigree by whole-exome sequencing and collected all KCNH2 variants with consensus based on publications. Methods: WES was performed on the proband of this pedigree to reveal the underlying cause of sudden cardiac death (SCD). The variant found was validated and segregated by polymerase chain reaction and Sanger sequencing. Based on the literature review, KCNH2 variants were retrospectively analyzed to identify pathogenic variants, likely pathogenic variants, and variants of uncertain significance by using different prediction tools. Results: WES identified an autosomal dominant nonsense variant, c.1425C>A: p.Tyr475Ter, in the KCNH2 gene, which appeared to be the most likely cause of LQTS in this pedigree. Moreover, our comprehensive literature review yielded 511 KCNH2 variants in association with the LQTS phenotype, with c.3002G>A (CADD Phred=49) being the most pathogenic variant. Conclusions: Variants in the KCNH2 gene are considered a major cause of LQTS worldwide. The detected c.1425C>A is a novel variant to be reported from Iran for the first time. This result indicates the importance of KCNH2 screening in a pedigree with SCD cases.

A novel stop-gain pathogenic variant in the KCNQ1 gene causing long QT syndrome 1.

BACKGROUND: Inherited primary arrhythmias, such as long QT (LQT) syndromes, are electrical abnormalities of the heart mainly due to variants in 3 genes. We herein describe a novel stop-gain pathogenic variant in the KCNQ1 gene in an Iranian child with LQT syndrome 1. METHODS: The patient and his family underwent clinical evaluation, electrocardiographic Holter monitoring, and whole-exome sequencing. Sanger sequencing and segregation analysis were used to confirm the variant in the patient and his family, respectively. The pathogenicity of the variant was checked via an in silico analysis. RESULTS: The proband suffered from bradycardia and had experienced syncope without stress. The corrected QT interval was 470 ms (the Schwartz score ≥ 3.5), and the Holter monitoring showed sinus rhythm, infrequent premature atrial contractions, and a prolonged QT interval in some leads. Whole-exome and Sanger sequencing showed c.968G > A in 3 affected family members. According to the American College of Medical Genetics and Genomics criteria, c.968G > A was classified as a pathogenic variant. CONCLUSIONS: The KCNQ1 gene is the main cause of LQT syndromes in our population. The common genes of LQT syndromes should be studied in our country's different ethnicities to determine the exact role of these genes in these subpopulations.

A novel stop-gain pathogenic variant in FLT4 and a nonsynonymous pathogenic variant in PTPN11 associated with congenital heart defects.

BACKGROUND: Congenital heart defects (CHDs) are the most common congenital malformations, including structural malformations in the heart and great vessels. CHD complications such as low birth weight, prematurity, pregnancy termination, mortality, and morbidity depend on the type of defect. METHODS: In the present research, genetic analyses via whole-exome sequencing (WES) was performed on 3 unrelated pedigrees with CHDs. The candidate variants were confirmed, segregated by PCR-based Sanger sequencing, and evaluated by bioinformatics analysis. RESULTS: A novel stop-gain c.C244T:p.R82X variant in the FLT4 gene, as well as a nonsynonymous c.C1403T:p.T468M variant in the PTPN11 gene, was reported by WES. FLT4 encodes a receptor tyrosine kinase involved in lymphatic development and is known as vascular endothelial growth factor 3. CONCLUSIONS: We are the first to report a novel c.C244T variant in the FLT4 gene associated with CHDs. Using WES, we also identified a nonsynonymous variant affecting protein-tyrosine phosphatase, the non-receptor type 11 (PTPN11) gene. The clinical implementation of WES can determine gene variants in diseases with high genetic and phenotypic heterogeneity like CHDs.

Novel homozygous stop-gain pathogenic variant of PPP1R13L gene leads to arrhythmogenic cardiomyopathy.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is a heritable cardiac disease with two main features: electric instability and myocardial fibro-fatty replacement. There is no defined treatment except for preventing arrhythmias and sudden death. Detecting causative mutations helps identify the disease pathogenesis and family members at risk. We used whole-exome sequencing to determine a genetic explanation for an ACM-positive patient from a consanguineous family. METHODS: After clinical analysis, cardiac magnetic resonance, and pathology, WES was performed on a two-year-old ACM proband. Variant confirmation and segregation of available pedigree members were performed by PCR and Sanger sequencing. The PPP1R13L gene was also analyzed for possible causative variants and their hitherto reported conditions. RESULTS: We found a novel homozygous stop-gain pathogenic variant, c.580C > T: p.Gln194Ter, in the PPP1R13L gene, which was confirmed and segregated by PCR and Sanger sequencing. This variant was not reported in any databases. CONCLUSIONS: WES is valuable for the identification of novel candidate genes. To our knowledge, this research is the first report of the PPP1R13L c.580C > T variant. The PPP1R13L variant was associated with ACM as confirmed by cardiac magnetic resonance and pathology. Our findings indicate that PPP1R13L should be included in ACM genetic testing to improve the identification of at-risk family members and the diagnostic yield.