Digenic inheritance in autosomal recessive non-syndromic hearing loss cases carrying GJB2 heterozygote mutations: Assessment of GJB4, GJA1, and GJC3

Objective: Autosomal recessive non-syndromic hearing loss (ARNSHL) can be caused by many genes. However, mutations in the GJB2 gene, which encodes the gap-junction (GJ) protein connexin (Cx) 26, constitute a considerable proportion differing among population. Between 10 and 42 percent of patients with recessive GJB2 mutations carry only one mutant allele. Mutations in GJB4, GJA1, and GJC3 encoding Cx30.3, Cx43, and Cx29, respectively, can lead to HL Combination of different connexins in heteromeric and heterotypic GJ assemblies is possible. This study aims to determine whether variations in any of the genes GJB4, GJA1 or GJC3 can be the second mutant allele causing the disease in the digenic mode of inheritance in the studied GJB2 heterozygous cases. Methods: We examined 34 unrelated GJB2 heterozygous ARNSHL subjects from different geographic and ethnic areas in Iran, using polymerase chain reaction (PCR) followed by direct DNA sequencing to identify any sequence variations in these genes. Restriction fragment length polymorphism (RFLP) assays were performed on 400 normal hearing individuals. Results: Sequence analysis of GJB4 showed five heterozygous variations including cA51C>A, c.219C>T, c.507C>G, c.155_158delTCTG and c.542C>T, with only the latter variation not being detected in any of control samples. There were three heterozygous variations including c.758C>T, c.717G>A and c.3*dupA in GJA1 in four cases. We found no variations in GJC3 gene sequence. Conclusion: Our data suggest that GJB4 c.542C>T variant and less likely some variations of GJB4 and GJA1, but not possibly GJC3, can be assigned to ARNSHL in GJB2 heterozygous mutation carriers providing clues of the digenic pattern. (C) 2012 Elsevier Ireland Ltd. All rights reserved

Mutation screening of GJB2 and GJB6 and genetic linkage study of three prevalent DFNB loci in Iranian families with autosomal recessive non-syndromic hearing loss

Background and aim: The incidence of prelingual hearing loss (HL) is about 1 in 1000 neonates of which, more than 60% of cases are inherited. Non-syndromic HL (NSHL) is extremely heterogeneous: more than 100 loci have been identified. The most common form of NSHL is the autosomal recessive form (ARNSHL). Here, we have investigated CX26 (GJB2) and CX30 (GJB6) gene mutation and linkage analysis of 3 known loci in Iranian families. Methods: A cohort of 36 big ARNSHL pedigrees from 7 provinces of Iran was investigated. All of the families were examined for the presence of GJB2 and GJB6 (del D13S1830 and del D13S1854) mutations using direct sequencing and multiplex PCR, respectively. The negative mutations pedigrees for the above- mentioned mutations, were then tested for the linkage to the 3 known loci, including DFNB3(MYO7A), DFNB4(SLC26A4) and DFNB7/11(TMC1), using STR markers and conventional PCR and PAGE. Results: Six families had GJB2 mutations. No GJB6 mutation was found. Totally, 3 families showed linkage to DFNB4 and 1 family was linked to DFNB7/11. Conclusion: DFNB1 (GJB2) and DFNB4 are the main causes of ARNSHL in our study samples and GJB6 mutations are apparently absent in the Iranian populatio

GJB2 mutations causing autosomal recessive non-syndromic hearing loss (ARNSHL) in two Iranian populations: Report of two novel variants

OBJECTIVE: Hereditary hearing loss (HL) is a noticeable concern in medicine all over the world. On average, 1 in 166 babies born are diagnosed with HL in Iran, which makes it a major public health issue. Autosomal recessive non-syndromic HL (ARNSHL) is the most prevalent form of HL. Although over 60 genes have been identified for ARNSHL, GJB2 mutations are the most prevalent causes of ARNSHL in many populations. Previous studies have estimated the average frequency of GJB2 mutations to be between 16 and 18% in Iran, but would vary among different ethnic groups. In the present study, we aimed to determine the frequency and mutation profile of 70 deaf patients from two different provinces (center and west) of Iran. METHODS: We enrolled 70 Iranian deaf patients with ARNSHL from Isfahan (40 family) and Hamedan (30 family) provinces. After extraction of genomic DNA, the entire coding region of GJB2 was directly sequenced in all patients. Multiplex PCR was used for detection of del(GJB6-D13S1830) and del(GJB6-D13S1854) in the GJB6 gene. In silico analyses were also performed by available software tools. RESULTS: A total of eleven different mutations were detected, nine of which were previously reported and the other two (c.130T > G and c.178T > G) were novel. Homozygous GJB2 mutations were observed in 22.5% and 20% of all the subjects from Isfahan and Hamedan provinces, respectively. c.35delG was the most frequent mutation. One compound heterozygous genotype (c.358_360delGAG/c.35delG) was observed for c.35delG. Screening for the two GJB6 deletions did not reveal any positive sample among heterozygous or GJB2 negative samples. CONCLUSIONS: The present study suggests that mutations in the GJB2 gene specially c.35delG are important causes of ARNSHL in the center and west of Iran. Totally, 15% of the patients were heterozygous carriers. Further investigation is needed to detect the genetic cause of HL in the patients with monoallelic GJB2 mutations

Genetic Linkage Analysis of 15 DFNB Loci in a Group of Iranian Families with Autosomal Recessive Hearing Loss

Background: Hearing loss (HL) is the most frequent sensory birth defect in humans. Autosomal recessive non-syndromic HL (ARNSHL) is the most common type of hereditary HL. It is extremely heterogeneous and over 70 loci (known as DFNB) have been identified. This study was launched to determine the relative contribution of more frequent loci in a cohort of ARNSHL families. Methods: Thirty-seven Iranian families including 36 ARNSHL families and 1 family with Pendred syndrome each with >= 4 affected individuals, from seven provinces of Iran, were ascertained. DFNB1 contribution was initially studied by DNA sequencing of GJB2 and linkage analysis using the relative STR markers. The excluded families were then subjected to homozygosity mapping for fifteen ARNSHL loci. Results: Sixteen families were found to be linked to seven different known loci, including DFNB I (6 families), DFNB4 (3 families +1 family with Pendred syndrome), DFNB63 (2 families), DFNB2 (1 family), DFNB7/11 (1 family), DFNB9 (1 family) and DFNB21 (1 family). DNA sequencing of the corresponding genes is in progress to identify the pathogenic mutations. Conclusion: The genetic causes were clarified in 43.2% of the studied families, giving an overview of the causes of ARNSHL in Iran. DFNB4 is ranked second after DFNB1 in the studied cohort. More genetic and epigenetic investigations will have to be done to reveal the causes in the remaining families

Mutation analysis of GJB2 and GJB6 genes and the genetic linkage analysis of five common DFNB loci in the Iranian families with autosomal recessive non-syndrom

The incidence of pre-lingual hearing loss (HL) is about 1 in 1000 neonates. More than 60% of cases are inherited. Non-syndromic HL (NSHL) is extremely heterogeneous: more than 130 loci have been identified so far. The most common form of NSHL is the autosomal recessive form (ARNSHL). In this study, a cohort of 36 big ARNSHL pedigrees with 4 or more patients from 7 provinces of Iran was investigated. All of the families were examined for the presence of GJB2 and GJB6 (del D13S1830 and del D13S1854) mutations using direct sequencing and multiplex PCR methods, respectively. The negative pedigrees for the above-named genes were then tested for the linkage to 5 known loci including DFNB3 (MYO7A), DFNB4 (SLC26A4), DFNB7/11 (TMC1), DFNB21 (TECTA) and DFNB59 (PJVK) by genotyping the corresponding STR markers using PCR and PAGE. Six families had GJB2 mutations. No GJB6 mutation was found. Totally, 3 families showed linkage to DFNB4, 1 family to DFNB7/11 and 1 family to DFNB21. No family was linked to DFNB59. GJB2 included 16.6% of the causes of ARNSHL in our study. In the remaining negative families, DFNB4 accounted for 10% of the causes. Other loci including DFNB7/11 and DFNB21 were each responsible for 3.3% of the etiology. Thus, DFNB1(GJB2) and DFNB4 are the main causes of ARNSHL in our study and GJB6 mutations (del D13S1830, del D13S1854), DFNB3 and DFNB59 were absent. Totally, 30.5% of the ARNSHL etiology was found in this study

Screening of 10 DFNB Loci Causing Autosomal Recessive Non-Syndromic Hearing Loss in Two Iranian Populations Negative for GJB2 Mutations.

BACKGROUND: Autosomal recessive non-syndromic hearing loss (ARNSHL), one of the global public health concerns, is marked by a high degree of genetic heterogeneity. The role of GJB2, as the most common cause of ARNSHL, is only <20% in the Iranian population. Here, we aimed to determine the relative contribution of several apparently most common loci in a cohort of ARNSHL Iranian families that were negative for the GJB2 mutations. METHODS: Totally, 80 Iranian ARNSHL families with 3 or more affected individuals from Isfahan and Hamedan provinces, Iran were enrolled in 2017. After excluding mutations in the GJB2 gene via Sanger sequencing, 60 negative samples (30 families from each province) were analyzed using homozygosity mapping for 10 ARNSHL loci. RESULTS: Fourteen families were found to be linked to five different known loci, including DFNB4 (5 families), DFNB2 (3 families), DFNB7/11 (1 family), DFNB9 (2 families) and DFNB3 (3 families). CONCLUSION: Despite the high heterogeneity of ARNSHL, the genetic causes were determined in 23.5% of the studied families using homozygosity mapping. This data gives an overview of the ARNSHL etiology in the center and west of Iran, used to establish a diagnostic gene panel including most common loci for hearing loss diagnostics. Copyright© Iranian Public Health Association & Tehran University of Medical Sciences. KEYWORDS: Autosomal recessive non-syndromic hearing loss (ARNSHL); DFNB loci; Homozygosity mapping; Ira

Estrogen receptor-α gene codon 10 (T392C) polymorphism in Iranian women with breast cancer: a case study

A case study was conducted to establish a database of polymorphisms in Iranian population in order to compare Western and Iranian (Middle East) distributions and to evaluate ESR1 polymorphism as an indicator of clinical outcome. The ESR1 gene was scanned in Iranian patients newly diagnosed invasive breast tumors, (150 patients) and in healthy individuals (147 healthy control individuals). PCR single-strand conformation polymorphism methodology and direct sequencing were performed. The silent single nucleotide polymorphism (SNPs) was performed, as reported previously in other studies, but at significantly different frequencies, with further increasing predictive accuracy in Iranian population. Data suggest that ESR1 polymorphisms are correlated with various aspects of breast cancer in Iranian ESR1 genotype, as determined during pre-surgical evaluation, might represent a surrogate marker for predicting breast cancer

Applications of comparative genomic hybridization in cancer and genetic disorders: a review article

&quot;n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Since the recognition of true number of human chromosomes in 1956, many techniques have been developed to detect chromosomal aberrations. A number of those, such as karyotyping and fluorescence in situ hybridization (FISH), are valuable tools in both research and diagnostics. But these techniques have defects that limit their application. One of the important limitations is resolution; resolution limitations make it impossible to detect small aberrations. The other major defect is the disability to analyze whole genome. In 1997 Solinas-Toldo introduced a new technique that could cover other techniques&apos; defects. This new technique called microarray-based comparative genomic hybridization (array CGH). Array CGH, with the powerful resolution of FISH and also the ability of whole genome analysis in single experiment accelerated the genetic research. Array CGH has resulted in to a great progress in oncology and genetic disorders research. In addition, this technique has the ability to be used in diagnostics too. This review article, witch include the data of recent published papers and our experiences, gives an overview of the array CGH and compare it with the other molecular cytogenetic techniques. Its application in oncology and genetic disorder is also discussed. &amp;nbsp