Association of the TCF7L2 rs12255372 (G/T) variant with type 2 diabetes mellitus in an Iranian population

In various populations worldwide, common variants of the TCF7L2 (Transcription factor 7-like 2) gene are associated with the risk of type 2 diabetes mellitus (T2DM). The aim was to investigate the association between rs12255372 (G/T) polymorphism in the TCF7L2 gene and T2DM in an Iranian population. 236 unrelated patients with T2DM, and 255 normoglycemic controls without diabetes were studied. The PCR-RFLP method was used for genotyping rs12255372 (G/T) polymorphism, and the SPSS version 18.0 for Windows for statistical analysis. The minor T allele of TCF7L2 rs12255372 was found to significantly increase the risk of T2DM, with an allelic odds ratio (OR) of 1.458 (95% CI 1.108-1.918, p = 0.007). A significant difference in TT genotype was observed between T2DM patients and normoglycemic controls (OR 2.038, 95% CI 1.147-3.623; p = 0.014). On assuming dominant and recessive models, ORs of 1.52 [95% CI (1.05-2.21) p = 0.026)] and 1.74 [95% CI (1.01-3.00) p = 0.043] were obtained, respectively, thereby implying that the co-dominant model would best fit the susceptible gene effect. This study further confirms the TCF7L2 gene as enhancing susceptibility to the development of T2DM. © 2012, Sociedade Brasileira de Genética

Association of interleukin-1 gene cluster polymorphisms and haplotypes with multiple sclerosis in an Iranian population

Multiple sclerosis (MS) is a multi-factorial autoimmune disease of the central nervous system. The exact etiology of MS is still unknown. Due to the important roles that cytokines play as mediators in immune and inflammatory responses, we have evaluated the association of IL-1 gene cluster polymorphisms and haplotypes with MS susceptibility in 306 unrelated MS patients and 312 healthy matched controls. A significant association was found for the IL-1β + 3953 T allele [OR = 1.43, 95% CI (1.14-1.79), P value = 0.002, Pc= 0.01] and for IL-1β + 3953 T/T genotype and MS risk [OR = 1.92, 95% CI (1.25-2.96), P value = 0.005, Pc= 0.01]. Interestingly, the genotypes of the polymorphisms remained significant under recessive, co-recessive and dominant models. However, no significant differences were found between MS patients and controls in the genotype and allele frequencies of the IL-1β - 511, - 31 and IL-1Ra polymorphisms. Haplotype analysis for IL-1β - 31 and IL-1β - 511, with moderate linkage disequilibrium (LD), using the EM algorithm revealed a significant global association of haplotype differences between the two groups. Lower presence of two haplotypes (H3: C-T and H4: T-C) was observed in the MS patients than healthy controls. However, after applying Bonferroni's correction the differences were not significant. To our knowledge, this is the first study reporting the association of the IL-1β + 3953 gene polymorphism and MS susceptibility. © 2015 Elsevier B.V

Association of P1635 and P1655 polymorphisms in dysbindin (DTNBP1) gene with schizophrenia

Alizadeh F, Tabatabaiefar MA, Ghadiri M, Yekaninejad MS, Jalilian N, Noori-Daloii MR. Association of P1635 and P1655 polymorphisms in dysbindin (DTNBP1) gene with schizophrenia. Objectives: Schizophrenia (SCZ) is a severe psychiatric disorder with a lifetime prevalence of approximately 1 in most of the populations studied. SCZ is multifactorial with the contribution of multiple susceptibility genes that could act in conjunction with epigenetic processes and environmental factors. There is some evidence supporting the association between genetic variants in dysbindin (DTNBP1) gene and SCZ in populations. In this study, we investigated the association between polymorphisms P1635 and P1655 in dysbindin gene with SCZ. Methods: Totally, 115 unrelated patients with SCZ and 117 unrelated healthy volunteers were studied. Genomic DNA was extracted from blood. Genotyping was done with the PCR-RFLP method. The allele and genotype associations were analysed with �2 test. The Benjamini-Hochberg procedure was used to correct p values for multiple comparisons. Results: The results showed no significant difference between patients and controls in allelic frequencies or genotypic distributions of SNP P1635 (p = 0.809), but a significant difference between the case and control groups for SNP P1655 (p = 0.009) was found. We could also find a significant positive association between A-C haplotype and SCZ (OR = 1.7, 95 CI 1.18-2.42; p = 0.004, pc = 0.02) and a protective effect for A-G haplotype (p = 0.003, OR = 0.57, 95 CI 1.18-2.42; p = 0.003, pc = 0.02). Conclusion: This study may provide further support for the association between SNP polymorphisms in DTNBP1 and SCZ in the Iranian population. Studies with more markers and subjects for various populations will be necessary to understand the genetic contribution of the gene to the development of SCZ. © 2011 John Wiley & Sons A/S

A novel mutation in the PAX3 gene causes Waardenburg syndrome type I in an Iranian family

Objectives: Sensorineural hearing impairment (HI) is one of the most frequent congenital defects, with a prevalence of 1 in 500 among neonates. Although there are over 400 syndromes involving HI, most cases of HI are nonsyndromic (70), 20 of which follow autosomal dominant mode of inheritance. Waardenburg syndrome (WS) ranks first among autosomal dominant syndromic forms of HI. WS is characterized by sensorineural hearing impairment, pigmentation abnormalities of hair and skin and hypoplastic blue eyes or heterochromia iridis. WS is subdivided into four major types, WS1-WS4. WS1 is diagnosed by the presence of dystopia canthorum and PAX3 is the only gene involved. This study aims to determine the pathogenic mutation in a large Iranian pedigree affected with WS1 in order to further confirm the clinical diagnosis. Methods: In the present study, a family segregating HI was ascertained in a genetic counseling center. Upon clinical inspection, white forelock, dystopia canthorum, broad high nasal root and synophrys, characteristic of WS1 were evident. In order to clarify the genetic etiology and confirm the clinical data, primers were designed to amplify exons and exon-intron boundaries of the responsible gene, PAX3 with 10 exons, followed by the Sanger DNA sequencing method. Results: Genetic analysis of PAX3 revealed a novel mutation in PAX3 (c.1024₁₀₄₀ del AGCACGATTCCTTCCAA). Our data provide genotype-phenotype correlation for the mutation in PAX3 and WS1 in the studied family, with implications for genetic counseling, which necessitates detailed clinical inspection of HI patients to distinguish syndromic HI from the more common non-syndromic cases. Conclusion: Our results reveal the value of phenotype-directed genetic analysis and could further expand the spectrum of PAX3 mutations. © 2015 Elsevier Ireland Ltd

Molecular and clinical characterization of Waardenburg syndrome type I in an Iranian cohort with two novel PAX3 mutations

Waardenburg syndrome (WS) is a disease of abnormal neural-crest derived melanocyte development characterized by hearing loss and pigmentary disturbances in hair, eyes and skin. WS is subdivided into four major types, WS1-WS4, where WS1 is recognized by the presence of dystopia canthorum, with PAX3 being the only known gene involved. This study aimed at investigating PAX3 mutations and clinical characteristics of WS1 in a group of Iranian patients. A total of 12 WS1 patients from four unrelated Iranian families were enrolled. Waardenburg consortium guidelines were used for WS1 diagnosis. A detailed family history was traced and a thorough clinical examination was performed for all participants. Furthermore, WS1 patients underwent screening for PAX3 mutations using PCR-sequencing.Dystopia canthorum, broad high nasal root and synophrys were observed in all patients. Early graying, hair discoloration, hypoplastic blue eyes (characteristic brilliant blue iris) and hearing loss were the most common features observed, while heterochromia iridis was the least frequently observed sign among the studied Iranian WS1 patients. Genetic analysis of PAX3 revealed four mutations including c.667C > T, c.784C > T, c.951delT and c.451 + 3A > C. Two of the four mutations reported here (c.951delT and c.451 + 3A > C) are being reported for the first time in this study.Our data provide insight into genotypic and phenotypic spectrum of WS1 in an Iranian series of patients. Our results expand the spectrum of PAX3 mutations and may have implications for the genetic counseling of WS in Iran. © 2015 Elsevier B.V

A comprehensive genetic and clinical evaluation of Waardenburg syndrome type II in a set of Iranian patients

Waardenburg syndrome (WS) is a neurocristopathy with an autosomal dominant mode of inheritance, and considerable clinical and genetic heterogeneity. WS type II is the most common type of WS in many populations presenting with sensorineural hearing impairment, heterochromia iridis, hypoplastic blue eye, and pigmentary abnormalities of the hair and skin. To date, mutations of MITF, SOX10, and SNAI2 have been implicated in the pathogenesis of WS2. Although different pathogenic mutations have been reported in many ethnic groups, the data on Iranian WS2 patients is insufficient. 31 WS2 patients, including 22 men and 9 women from 14 families were included. Waardenburg consortium guidelines were employed for WS2 diagnosis. WS2 patients underwent screening for MITF, SOX10, and SNAI2 mutations using direct sequencing and MLPA analysis. Clinical evaluation revealed prominent phenotypic variability in Iranian WS2 patients. Sensorineural hearing impairment and heterochromia iridis were the most common features (67 and 45, respectively), whereas anosmia was the least frequent phenotype. Molecular analysis revealed a de novo heterozygous c.640C > T (p.R214X) in MITF and a de novo heterozygous SOX10 gross deletion in the study population. Our data help illuminate the phenotypic and genotypic spectrum of WS2 in an Iranian series of patients, and could have implications for the genetic counseling of WS in Iran. © 2018 Babol University of Medical Sciences