Investigating Seven Recently Identified Genes in 100 Iranian Families with Autosomal Recessive Non-syndromic Hearing Loss

Objectives: Hearing loss (HL) is the most common sensory disorder, and affects 1 in 1000 newborns. About 50% of HL is due to genetics and 70% of them are non-syndromic with a recessive pattern of inheritance. Up to now, more than 50 genes have been detected which are responsible for autosomal recessive non-syndromic hearing loss, (ARNSHL). In  Iran, HL is one of the most common disabilities due to consanguineous marriages. The aim was to investigate the prevalence of three new ARHL genes (GJB4, GJC3, and SLITRK6) reported in neighboring countries among Iranian families with ARNSHL. Methods: One hundred unrelated families with at least two affected siblings in consanguineous marriage, who were negative for GJB2 gene mutations, were selected. By using three STR markers for each gene, homozygosity mapping was performed. Results: Two families showed linkage to GJB4, six families were linked to GJC3 and only one family linked to SLITRK6. The samples of these families who showed linkage were sent for Sanger sequencing to detect the causative mutations. However, after analyzing the sequencing results, no mutation could be detected in either of the families. Molecular analysis for these nine families is underway in order to determine the pathogenic mutations using whole exome sequencing. Discussion: These data demonstrate a very low prevalence of mutation in these three genes (GJB4, GJC3, and SLITRK6) in the Iranian population, since no mutation was detected in our study group of 100 families

Identification of a homozygous frameshift mutation in the FGF3 gene in a consanguineous Iranian family: First report of labyrinthine aplasia, microtia, and microdontia syndrome in Iran and literature review

Abstract Background To date, over 400 syndromes with hearing impairment have been identified which altogether constitute almost 30% of hereditary hearing loss (HL) cases around the globe. Manifested as complete or partial labyrinthine aplasia (severe malformations of the inner ear structure), type I microtia (smaller outer ear with shortened auricles), and microdontia (small and widely spaced teeth), labyrinthine aplasia, microtia, and microdontia (LAMM) syndrome (OMIM 610706) is an extremely rare autosomal recessive condition caused by bi‐allelic mutations in the FGF3 gene. Methods Using the whole‐exome sequencing (WES) data of the proband, we analyzed a consanguineous Iranian family with three affected members presenting with congenital bilateral HL, type I microtia, and microdontia. Results We discovered the homozygous deletion c.45delC in the first exon of the FGF3 gene, overlapping a 38.72 Mb homozygosity region in chromosome 11. Further investigations using Sanger sequencing revealed that this variant co‐segregated with the phenotype observed in the family. Conclusion Here, we report the first identified case of LAMM syndrome in Iran, and by identifying a frameshift variant in the first exon of the FGF3 gene, our result will help better clarify the phenotype–genotype relation of LAMM syndrome

Association between Cytochrome P450 2 C9 and Vitamin K Epoxide Reductase Complex Subunit 1 Polymorphisms with Warfarin dose among Iranian Patients

Background: Warfarin is a common anticoagulant drug that has a narrow therapeutic index; higher dose causes excessive bleeding and lower dose leads to cerebrovascular clotting and stroke in patients. Genetic factors that have been associated with warfarin response are the genes of cytochrome P450 2C9 (CYP2C9), which metabolize the more active S-enantiomer of warfarin, and vitamin K epoxide reductase (VKOR), the target site for warfarin. The present study was conducted to investigate the association between CYP2C9*2, CYP2C9*3 and VKORC1 (-1639 G>A) polymorphisms with warfarin daily dose on &nbsp;Iranian patients under warfarin treatment. Materials and Methods: This study is comprised of 118 Iranian patients on warfarin treatment who attended the PT Clinic. Genotyping of CYP2C9*2, CYP2C9*3 and VKORC1 (-1639 G>A) was performed by PCR-RFLP method. Multiple regression model was performed for statistical analyses and P<0.05 was considered as significance level. Results: The allelic frequencies of CYP2C9*2 and CYP2C9*3 were 19% and 7%, respectively. Patients with &ge;1 CYP2C9 variant allele had a significantly lower mean warfarin daily dose compared with patients with the wild-type genotype. The allelic frequencies of VKORC1 were 14.4%, 57.6% and 27.9% for GG, GA, and AA genotypes, respectively. The mean (SD) warfarin daily dose in patients with the VKORC1 (&ndash;1639) GG genotype was significantly higher than GA and AA patients. Conclusion: CYP2C9*2, CYP2C9*3 and VKORC1 (-1639 G>A) polymorphisms had significant association with warfarin daily dose; furthermore, the daily warfarin dose was not influenced by age, height, weight and sex

Association of Polymorphisms at LDLR Locus with Coronary Artery Disease Independently from Lipid Profile

Coronary artery disease (CAD) is the leading cause of mortality in many parts of the world. Genome-wide association studies (GWAS) have identified several genetic variants associated with CAD in Low-density lipoprotein receptor (LDLR) locus. This study was evaluated the possible association of genetic markers at LDLR locus with CAD irrespective to lipid profile and as well as the association of these SNPs with severity of CAD in Iranian population. Sequencing of 2 exons in LDLR gene (Exon 2, 12) and part of intron 30 of SMARCA4 gene include rs1122608, was performed in 170 Iranian patients angiographically confirmed CAD and 104 healthy controls by direct sequencing. Sullivan's scoring system was used for determining the severity of CAD in cases. Our results showed that homozygote genotypes of rs1122608 (P<0.0001), rs4300767 (P<0.005) and rs10417578 (p<0.007) SNPs have strong protective effects on the CAD. In addition, we found that rs1122608 (GT or TT) was at higher risk of three vessel involvement compared to single vessels affecting (P=0.01)

Analysis of the association Hind III Polymorphism of Lipoprotein Lipase gene on the risk of coronary artery disease

Background: Coronary artery disease (CAD) is one of the leading causes of death and disability around the world. Interaction between genetic and environmental factors determines susceptibility of an individual to develop coronary artery disease . Lipoprotein lipase (LPL) play an important role in the metabolism of HDL-C ( High Density Lipoprotein Cholesterol ), LDL-C (Low Density Lipoprotein Cholesterol ) and triglycerides (TG). Dysfunction of LPL as a result of genetic variants of lipoprotein lipase gene is associated with increased risk of CAD. The aim of the present study was to investigate the relationship between the risk of coronary artery disease and LDL-C, HDL-C and TG (triglycerides) levels by lipoprotein lipase gene Hind III polymorphism. Materials and Methods: A total of 202 subjects including 114 patients with coronary artery disease and 88 control participated in this study. The Hind III polymorphism of the lipoprotein lipase gene was determined by PCR- RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism) . In the presence and absence of restriction site, the genotypes are described H+/+ , H-/- respectively. Results: In this survey, a highly significant association between the frequent H+/+ genotype and unfavorable TG levels was observed in our population . For the Hind III genotypes, within the healthy subjects (n=88), the H+/+ genotype was found in 67 individuals (58.8%), H-/+ genotype in 38 individuals (33.3%) , and 9 individuals (7.8%) carried the H-/- genotype. Within the CAD group (n=114), 47 individuals (53.4%) with H+/+ genotype, 36 (41%) with H-/+ genotype, and 5 (5.6%) carried the H-/- genotype. Conclusion: There was a significant difference between the distribution of LPL–Hind III genotypes and the healthy subjects and the patients with CAD (P<0.05, 0. 645). LPL–Hind III polymorphisms were not detected as independent risk factors for CAD in this study group, but had significant associations with TG levels (P<0.05)

Exome sequencing utility in defining the genetic landscape of hearing loss and novel-gene discovery in Iran

Hearing loss (HL) is one of the most common sensory defects affecting more than 466 million individuals worldwide. It is clinically and genetically heterogeneous with over 120 genes causing non-syndromic HL identified to date. Here, we performed exome sequencing (ES) on a cohort of Iranian families with no disease-causing variants in known deafness-associated genes after screening with a targeted gene panel. We identified likely causal variants in 20 out of 71 families screened. Fifteen families segregated variants in known deafness-associated genes. Eight families segregated variants in novel candidate genes for HL: DBH, TOP3A, COX18, USP31, TCF19, SCP2, TENM1, and CARMIL1. In the three of these families, intrafamilial locus heterogeneity was observed with variants in both known and novel candidate genes. In aggregate, we were able to identify the underlying genetic cause of HL in nearly 30% of our study cohort using ES. This study corroborates the observation that high-throughput DNA sequencing in populations with high rates of consanguineous marriages represents a more appropriate strategy to elucidate the genetic etiology of heterogeneous conditions such as HL