محمد امین طباطبایی فر

Approximately 3% of the human genome is rich in GCs. These regions are often found in the promoter of genes, especially housekeeping genes and tumor suppressor genes. Amplification of these GC-rich regions can be challenging. Because the stability of GC-rich DNA sequences is higher, secondary structures are easily formed in these regions. Type 4 non-medullary thyroid carcinoma has been linked to the FOXE1 gene as a risk factor. FOXE1 belongs to a large family of transcription factors principal for the development of the thyroid gland's morphology.

With a high proportion of GC, a portion of the FOXE1 gene sequence cannot be amplified using the usual polymerase chain reaction. This work is an experimental study that deals with this issue.

The results of the present study showed that the Touchdown polymerase chain reaction, in combination with CO-amplification materials such as betaine and Dimethyl Sulfoxide (DMSO), is effective in amplifying the sequence of this region of the FOXE1 gene by destruction of the secondary structures formed in the sequence and increasing the reaction product.

Using this method, GC-rich regions in additional genes with a similar degree of GC as the FOXE1 gene can be amplified.

Tissue regeneration is the process of renewal and growth of damaging tissue. It is sometimes done by induction of an external biological factor(s) such as the Basic fibroblast growth factor (bFGF) which carries messages through its cellular receptor to induce biological processes such as cell growth, cell migration, cell survival, and cell differentiation. Due to the great importance of bFGF on cellular regeneration, in this study, we have concentrated on the effect of this factor on the regeneration of damaged muscle. In addition, the tumorigenic effect of this factor during this regenerative process was studied. In this study, we employed inbred mice. The cultured male mouse muscle cells were transplanted into the damaged muscle tissues of HLA_matched female mice. After about one month, selected samples from the transplanted regions of the female mice were analyzed. DNA was extracted from the samples and Sex determination was done to track the potential cell growth and repair by the introduced male cells in the presence and absence of bFGF. The tumorigenic effect of bFGF on this process was also assessed. We found that bFGF had a remarkable effect on damaged muscle regeneration compared to cells without injection of this factor, and more concentration of bFGF was determined to be more effective in muscle regeneration. However, no association was observed with tumorigenesis regarding bFGF injection. According to our findings, bFGF was effective in the regeneration of the injury site and confirmed the results of previous studies. However, no association was found with tumorigenesis.

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by severe developmental delay or intellectual disability caused by either disruption of the maternal UBE3A gene or deletion in the maternal 15q11-q13. Diagnosis of AS in two siblings with normal four-generation history was confirmed through a staged genetic evaluation, G-banding karyotype, Fluorescence in situ Hybridization analysis, and methylation pattern in 15q11-q13. Despite detecting impaired methylation patterns in the region of interest, distinguishing the imprinting defects from uniparental disomy (UPD) was not feasible since we did not have access to the parents' sample. However, regarding the low risk of AS recurrence within families with UPD in the literature and the healthy family history, mosaicism of cryptic imprinting center deletion in the mother's germline should be the most probable cause of AS recurrence in our cases.

The precision and time required for analysis of data in next-generation sequencing (NGS) depends on many factors including the tools utilized for alignment, variant calling, annotation and filtering of variants, personnel expertise in data analysis and interpretation, and computational capacity of the lab and its optimization is a challenging task. 

An application software was designed and implemented in C# for optimizing the third step of NGS data analysis. In this study, annotation, filtering, and interpretation of NGS data were specifically optimized for non-syndromic autosomal recessive hearing loss disease.

Whole-exome sequencing data of a patient with a pathogenic mutation confirmed by familial genetic analysis, which contained a total number of 671829 variants after primary analysis, were evaluated by the implemented software. After filtering the variants based on a predefined BED file, 508 variants remained. According to the patient’s pedigree, in the next step of analysis, homozygote variants were selected and only 187 variants remained. After applying the population frequency threshold of 0.6% on gnomeAD and ExAC databases, the number of variants reached 110 and 3, respectively. The identified pathogen was approved by the results of Sanger sequencing done for family co-segregation. This analysis took about 15 minutes on a moderate PC.

The designed software is a fully graphical one that has the capability of comparing, viewing, filtering, and merging input files without any coding. Moreover, it can construct a local database from the analyzed files and apply region constraints and user-defined thresholds on various fields of the database.

Diabetes mellitus is a group of metabolic disorders resulting in increased level of blood sugar. Type 1 Diabetes (T1D), Type 2 Diabetes (T2D) and monogenic diabetes are there major groups of diabetes. Maturity-onset diabetes of the young (MODY) is a monogenic diabetes that is frequently mistaken for T1D or T2D and it has 14 different subgroups. The aim of this study was to diagnose MODY and determine the frequency of its 2 major subgroups in Isfahan diabetic population.

In this descriptive-experimental study with the aim of determining type and the frequency of mutations in GCK and HNF1A genes in 26 families with MODY from Isfahan using genetic linkage analysis method and select of 4 markers for each gene. Linkage results was confirmed by fragment analysis and then all the exons of genes were sequenced in any linked families.

In this study from 26 families, 4 families were linked to markers of GCK gene and 3 families were linked to HNF1A gene. After sequencing of all exons of these 2 genes in the related families, variants were analyzed and their effects on diabetes were surveyed. There was no pathogenic mutation but some polymorphisms with increasing effects on susceptibility to diabetes were found.

in this study despite of the fact that some families were linked to markers of these 2 gene, and the results of other studies that mutations in these 2 genes are the frequent reasons of MODY, there were any pathogenic variant in any of the patients. So it seems that the genetic profile of this population is different from other studied populations.

Diabetes mellitus is a group of metabolic disorders in the body, accompanied with increasing blood sugar levels. Diabetes is classified into 3 groups: Type 1 (T1DM), Type 2 (T2DM) and monogenic diabetes. Maturity-onset diabetes of the young (MODY) is a monogenic diabetes that is frequently mistaken for T1D or T2D. The aim of this study was to diagnose MODY using non-genetic biomarkers and determine its frequency in the population of Isfahan province. This, in addition to saving time and cost, is important for prognosis and appropriate treatment.
In this analytical descriptive study 2085 diabetic patients with a 2-6 years of disease were examined and after assessing the clinical symptoms, in 57 cases with clinical symptoms for MODY, three markers (C-peptide, anti-GAD65 and anti-insulin (II)) were measured by ELISA method and compared with healthy cases and confirmed T1D and T2D patients.
In this analytical descriptive study, among 2085 diabetic patients, in 500 cases of them, the incidence of the disease was before the age of 25 years of old and after measuring 3 mentioned biochemical markers, 41 cases were negative for anti-GAD65 and anti-Insulin and had detectable C-peptide level and the differences in the levels of these three markers in suspected MODY group were meaningful (P The use of proprietary non-genetic biomarkers is very valuable for MODY detection and could be used alongside other clinical features to screen a large number of patients with diabetes. Ultimately, only suspect cases must be selected for genetic tests.

Hearing loss (HL) is a most common sensory deficit in humans and approximately one in 1,000 newborns has severe-to-profound HL. About 50% of HL cases are inherited and approximately 70 percent of HL cases are Non-syndromic that about 80 percent of this type of HL is inherited in recessive manner (ARNSHL). This is a heterogeneous disease and its prevalence is higher in developing countries. In Iran due to high rate of consanguinity has high frequency, too. The purpose of the present study was to investigate genetic linkage analysis of DFNB39 locus in families with autosomal recessive nonsyndromic HL from Khuzestan province.
In this descriptive laboratory study, to determine type and frequency of HGF mutations 300 individuals of 25 families from Khuzestan province with autosomal recessive nonsyndromic hearing loss were examined. Selected families in this study had consanguinity and had at least 2 patients and also they were negative for GJB2 gene mutations. Linkage analysis was performed by 6 markers STR (Short tandem repeats) which were located in or were tightly linked to DFNB39 locus conventional PCR and PAGE.
After examining different families, it was revealed non of the families did not show linkage to the DFNB39 locus. Lack of HGF gene mutations in mentioned family suggests that the HGF's mutations probably have no role in causing HL in the studied families.
Based on the results of this study, DFNB39 locus may not be important role in causing hearing loss of population studied. However, further studies are necessary to determine more precisely the role of this locus in hearing loss in Iranian population.

Gastric cancer (GC) is the fourth common cancer worldwide and the second cause of mortality among all cancers. Mutations in the CDH1 gene are the most common cause of hereditary diffuse gastric cancer (HDGC) and sporadic diffuse gastric cancer (SDGC). CDH1 gene encode for E-cadherin protein. We compared the nucleotide alterations and copy number variations in CDH1 gene between Iranian patients with HDGC and SDGC.
We evaluated 45 patients including 17 cases with HDGC and 28 cases with SDGC identified according to the histopathological criteria and familial history. DNA extraction was obtained from peripheral blood and formalin-fixed paraffin-embedded (FFPE) tissues. The DNA sequencing was completed using polymerase chain reaction (PCR) amplification of 16 exons of the CDH1 gene. Multiplex ligation-dependent probe amplification (MLPA) method was accomplished on samples with no pathogenic variants in sequencing.
Findings: Synonymous substitution of L116L and A692A was detected in patients with HDGC and SDGC; but non-synonymous substitution of D777E, c.889delA, and c.1177delA deletions only detected in patients with HDGC. MLPA results revealed one deletion in exon 1 of CDH1 gene in patients with HDGC and one deletion in exon 2, and one duplication in exon 9 of CDH1 gene in patients with SDGC.
According to the results, different variants in CDH1 gene was presented in patients with HDGC and SDGC that emphasis the survey of CDH1 variants and especially detected variants in this study in the diagnosis of diffuse gastric cancer disease.

Hearing loss (HL) is the most common sensorineural disorder affecting 1 in 1000 newborns. About 70% of genetic HL is classified as nonsyndromic deafness. Over 100 non-syndromic loci have been identified in autosomal recessive nonsyndromic hearing loss (ARNSHL). The aim of this study is identifying genetic cause of deafness by investigating genetic linkage analysis for DFNB24 locus (RDX gene) in ARNSHL families.
In this descriptive-experimental study, 400 samples from 25 Iranian consanguinity families with 3 or more patients, segregating as an ARNSHL, were selected from Khuzestan. Totally, 23 families were negative for GJB2 mutations (DFNB1) and were included. Six STR (Short Tandem Repeat) markers were selected, PCR amplification was done, and genotyping was performed by electrophoresis PCR product on polyacrylamide gel (PAGE). Several software tools such as Easy Linkage, SimWalk and HaploPainter were used for linkage analysis.
Following the study of genetic linkage of DFNB24 in hearing loss population of Kuzestan province, our findings showed no families to be linked to the DFNB24 locus and deafness.
Results of the present study showed that RDX mutations may have little role in the etiology of deafness in this province.

Hearing loss (HL) is the most common congenital defect in humans. One or two in thousand newborn babies have prelingual hearing loss. Autosomal recessive non-syndromic hearing loss (ARNSHL) is the most common form of hereditary deafness. Hearing loss is more common in the developing countries which is due to genetic and environmental (cultural -health factors) reasons. HL has a wide range of clinical demonstrations including: congenital or late onset, conductive or sensory-neural, syndromic or non-syndromic hearing loss. The goal of this project is to determine the portion of the DFNB21 (TECTA) in ARNSHL in families with negative GJB2 gene in Khuzestan province.
We studied 21 families with ARNSHL with at least 4 patients and negative for GJB2 mutations from Khuzestan province. Genetic linkage analysis was performed using STR markers linked to DFNB21 locus.
Following genetic linkage analysis and haplotyping, out of 21 families with ARNSHL, one family showed linkage to the DFNB21 (TECTA) locus.
The results of this project confirm other studies in Iran and give insight into the most common loci causing ARNSHL in Iran which could be helpful in research and clinic.

Hearing loss is a common sensorial disorder. There are approximately 360 million affected people all over the world. More than 50% of hearing loss is because of genetics factors. About 70% of inherited hearing loss is due to non-syndromic hearing impairment that Autosomal- recessive inheritance is responsible for about 80% of cases. Autosomal recessive non syndromic hearing loss is very heterogeneous and more than 50 genes have been identified for it. The aimof this study was to investigate the role of DFNB42 (ILDR1) and DFNB35 (ESRRB) mutations in 25 families with ARNSHL from Khuzestan Iran.
This descriptive study was based on linkage analysis and selected 6 STR markers for each locus. This study was performed for 300 individuals from 25 families that had at least two affected, also they had consanguineous marriage. In this study, it was investigated mutations of GJB2 and 3 families with positive result for mutation in GJB2, were excluded from our study.
With linkage analysis, none of selected families was linked to DFNB35 or DFNB42 loci. This study showed that the ILDR1 and ESRRB mutations have no role in hearing loss in studied families.
This study shows that mutations in ILDR1 and ESRRB genes have no important role in incidence of hearing loss in Khuzestan province. This result suggests that studying of other loci that are involved in deafness, can be helpful to identify genetic causes in this disease in the studied population.

Hearing loss, a sensorineural disorder, is one of the most common congenital impairments, occurring in approximately 1 in 500 newborns. Hearing loss is a highly heterogenic disease and half of the cases of deafness are attributed to genetic causes; environmental and unknown factors account for the remainder. Non-syndromic type forms 70% of hearing loss cases. Pattern of inheritance of nearly 80% of this type of HL is recessive autosomal. Iranian population provides a valuable genetic resource to study this kind of HL because of high ratio of consanguinity. In this study, genetic linkage of DFNB48 (CIB2) and DFNB98 (TSPEAR) is investigated in families with ARNSHL impairment from Khouzestan province.
In this descriptive study 300 individuals of 25 families with hearing loss were examined in order to determine type and frequency of mutation of DFNB48 and DFNB98 loci in Khouzestan province. Familie's selection had some criteria. Families with healthy parents, consanguineous marriage and negative result for mutations of GJB2 gene with at least two affected individuals were selected. 3 families which were detected positive for mutations of GJB2 gene were excluded from study. Linkage analysis was done for 22 families by using six STR markers which were located in or were tightly linked to each locus.
None of these families inspected by linkage analysis was linked to the DFNB48 or DFNB98 loci.
Considering these results it seems that CIB2 and TSPEAR genes mutations have not important roles in hearing loss in Khouzestan province.

Hearing loss is a common sensory impairment in humans which half of its causes are genetic reasons. Genetic hearing loss can be divided into the two types of syndromic and non-syndromic, which 80% of non-syndromic cases is Autosomal Recessive Non-Syndromic Hearing Loss. The aim of the present research is to determine the contribution of DFNB2 locus (MYO7A gene) in causing an autosomal recessive hearing loss in the one group of the deaf families of Khuzestan province.
This study was conducted on 26 families with autosomal recessive hearing loss (with 4 patients) and negative for GJB2 mutations in Khuzestan province. 22 families suffered from ARNSHL and 4 families suffered from Usher syndrome. Linkage analysis was performed by using STR (Short Tandem Repeat) markers related to DFNB2 locus. Each family’s genotype was determined by PCR-PAGE method. Furthermore, haplotypes drawing and LOD score calculations were performed.
From 26 families with hearing loss participating in this research, following genetic linkage analysis and haplotypes drawing, two families (7.7% of the families) showed linkage to DFNB2 locus. One family (4.5%) suffered from ARNSHL and another family suffered from Usher syndrome.
The results of the present research show that the contribution of DFNB2 locus in causing hearing loss in the population of Khuzestan province was similar to other studies conducted in Iran and this locus with other important loci should be considered to check in the hearing loss panel.

Hearing loss is a most common sensory deficit in humans. The hearing loss may be conductive, sensorineural, or mixed (syndromic or nonsyndromic), prelingual or postlingual. Due to the complexity of the hearing mechanism, it is not surprising that several hundred genes might be involved in causing hereditary hearing loss. So far 152 loci have been identified which are associated with the most common type of hearing loss. This study aimed to analyze genetic linkage of DFNB7/11 locus in families with autosomal recessive nonsyndromic hearing loss from Hamedan province.
In this descriptive laboratory study, 24 families from Hamedan province with autosomal recessive nonsyndromic hearing loss were examined. Selected families in this study had consanguinity and they were negative for GJB2 gene mutations. Linkage analysis was performed by 7 markers (STR) for DFNB7/11 locus.
After examining different families, one family of the 24 families (4.16%) showed linkage to the DFNB7/11 locus, but in examining different exons and promoter of TMC1 gene, no mutation was found. Lack of TMC1gene mutations in mentioned familyy suggests mutations exist in noncoding regions of TMC1 genes or new gene exists in this locus. SLINK value and LOD score of this family was 1.45 and 0.54 respectively.
Based on the results of this study, DFNB7/11 locus may not have important role in causing hearing loss of population studied, but further studies are necessary to determine more precisely the role of this locus in hearing loss in Iranian population.

Sensorineural hearing loss (SNHL) is the most common sensory disorder and 1 in every 500-1000 newborns is affected. Non-syndromic SNHL accounts for 70% of hereditary hearing loss and 80% of SNHL cases have an autosomal recessive mode of inheritance (ARNSHL). The Purpose of the recent study is genetic linkage analysis to determine the prevalence of DFNB40 and DFNB48 loci in studying families with ARNSHL from the western provinces of Iran.
In this study, 60 families from 3 provinces of Iran involving Hamedan, Kohgiluyeh and Boyer-Ahmad and Chaharmahal and Bakhtiari with autosomal recessive non syndromic hearing loss were examined. The selected families in this study were consanguineous and had at least two patients. They also were negative for GJB2 mutations. Linkage analysis was performed by using 6 markers short tandem repeat (STR) for the DFNB40 locus and 7 markers STR for the DFNB48 locus.
Findings: After examining different families, it was revealed that none of them showed linkage to the DFNB40 and DFNB48 loci.
The recent study suggests that DFNB40 and DFNB48 loci might not play an important role in causing hearing loss in the mentioned provinces. However, further studies are necessary to determine more precisely the role of these loci in the Iranian population.

Bilateral sensorineural hearing loss is one of the most frequent congenital defects, and it has the prevalence of one in thousand among the infants. The most cases of hearing impairment are nonsyndromic and about 80 percent of patients with sensorineural HE show authosomal recessive pattern. ARSNL is a very heterogenic defect for over 70 loci and 50 genes have been found. In this study, in order to prove the prevalence of DFNB59 mutations, we examined DFNB59 mutations in 54 families from 3 provinces of Iran including Hamedan, Kohgiluye& Boveir Ahmad and Chaharmahal Bakhtiari. The gene (PJVK) in this locus encodes Pejvakin protein (PJVK) and causes nerve stimulation to conduct. Selected families in this study have consanguinity and at least have two patients with the defect; they also are negative in having the GJB2 mutations. Six markers were selected for this locus and linkage analysis was performed. However, after examining different families, it was revealed that none of them had linkage to the DFNB59 locus. Therefore, this study suggests that that Pejvakin mutations might not play an important role in causing hearing loss in these provinces.

Hearing loss is a sensorineural impairment and is one of the most widespread congenital impairments with a prevalence of one in thousand among children. Studies have shown that 50 percent of congenital hearing loss have genetic causes and the remaining 50 percent are due to environment and unknown reasons; in addition, it is noted that this impairment is very heterogeneous. Almost 70 percent of cases are nonsyndromic with hearing loss presenting as the only impairment. About 80 percent of this type of hearing loss is inherited in recessive manner (ARNSHL). In this study, we determined the role of DFNB63 locus in a series of families in two western provinces of Iran. In this descriptive-laboratory study, to determine the prevalence of DFNB63 mutations in western provinces of Iran, we studied 150 individuals from 30 families in Hamadan and Kohgiluyeh and Boyer-Ahmad provinces. The selected families in this study were consanguineous, had at least 2 patients, and were negative for GJB2 mutations. Linkage analysis was performed using six appropriate short tandem repeats (STR) markers. With linkage analysis of selected families, no family was shown to be linked to the DFNB63 locus. It was shown that the LRTOMT mutations played no role in causing hearing loss in the studied families. The present study suggests that LRTOMT mutations may not be clinically important in causing autosomal recessive nonsyndromic hearing loss in the investigated provinces.

Hearing loss (HL) is one of the sensory, neurological disorders and is the highest rate of existing disorder at birth. More than 60% of deafness is hereditary. Genetic type of HL is divided into two groups, syndromic HL (SHL) and Non-syndromic HL (NSHL). Autosomal recessive non syndromic deafness (ARNSHL) occurs with the highest percentage (70%). This study aimed to determine genetic linkage of DFNB93 Locus in families with ARNSHL. The descriptive study was performed on 40 large pedigrees with at least two ARNSHL patients. They had healthy parents and most of consanguineous marriage. These cases were negative for GJB2 gene mutation in Chahar Mahal & Bakhtiari and Kohkiluyeh & Boyer Ahmad provinces of Iran. Then families were investigated for genetic linkage to the DFNB93 locus using STR markers, PCR and polyacrylamide gels. Results showed that one of the 40 families (2.5%) was linked to the DFNB93 locus. The value of SLINK (2.67), preliminary two-point LOD (2.05), and multipoint LOD (2.05) for this family was calculated. Based on the results of this study, DFNB93 locus has probably little role in deafness of studied population. Further investigations are necessary to determine the role of this locus in deafness in Iranian population more precisely.

The most common sensorineural defect in human is congenital hearing loss and genes have an incontestable role in the development of this defect. Many genetic mutations are known to be responsible in this heterogeneous disease. The most frequent mutations are GJB2 mutations followed by the SLC26A4 mutations. Recently، we published a report regarding the role of c. 637+1G>T mutation in CABP2 gene، causing hearing loss in three Iranian families. The present study was launched to analyze the role of this recently reported mutation in patients with sporadic hearing loss. One hundred and eighty three patients with moderate to profound sporadic hearing loss were included in this study. The mutation c. 637+1 G>T was investigated in patients using the PCR-RFLP method. PCR-RFLP findings revealed that the considered mutation was absent in subjects with sporadic hereditary hearing loss. The mutation c. 637+1 G>T in CABP2 gene did not play any roles in the investigated Iranian patients with sporadic hearing loss. Larger samples of different populations، and assessment of all exons and the promoter region of mentioned gene will help to determine the real role of this gene in producing hearing loss.

Hearing loss is a common sensory disorder that typically illustrates genetic heterogeneity in human populations. The incidence of congenital hearing loss is estimated at 1 in 500 births of which approximately 70% of cases are attributed to genetic factors. Genetic hearing impairment can be classified as either syndromic or non-syndromic and among non-syndromic hearing loss autosomal recessive (ALNSHL) accounts for approximately 75-80% of cases. This type of hearing loss is extremely heterogeneous and includes over 100 loci. For recessive deafness, most frequent genes are GJB2, SLC26A4, MYO15A, OTOF, and CDH23 in worldwide. This study aimed to determine the role of MYO15A (DFNB3) gene mutations in Iranian deaf population using linkage analysis.

To investigate the frequency of DFNB3 gene mutation, linkage analysis was performed in 30 Iranian families with over three deaf child and negative GJB2. The negative mutations pedigrees for these gene mutations were then tested for the linkage to DFNB3 (MYO15A) locus, using short tandem repeat (STR) markers.

Mutation 35delG was identified in 5 families out of 30 by sequencing the coding region of GJB2 gene. One family showed linkage to DFNB3 locus.

Based on the results of this study, DFNB3 locus is the third cause of deafness after DFNB1 (GJB2) and DFNB4 (SLC26A4).

Congenital hearing loss is the most common sensorineural defect in human. The most common genetic mutations in this disease are GJB2 mutations which are followed by SLC26A4 mutations. Following a report for the first time in the world insist on CABP2 gene interference in hearing loss production, the present study was launched to analyze this mutation in Iranian patients with hereditary hearing loss. This is a cross sectional study. Among samples with autosomal recessive familial hearing loss pattern, regarding pedigree and audiometric data 253 patients with moderate to profound hearing loss were selected and studied. The mutation c. 637+1G>T was investigated using PCR-RFLP method. PCR-RFLP findings revealed that c.637+1G>T mutation was absent in the deaf subjects with hereditary moderate to profound hearing loss in analyzed provinces. The mutation c.637+1G>T in CABP2 gene does not play any role in the investigated Iranian subjects with hereditary hearing loss.

In this study we performed linkage analysis on a large X linked RSA pedigree to find a novel susceptibility locus for RSA. A linkage scan using 11 microsatellites was performed in 27 members of a large pedigree of hereditary X-linked RSA. Two point parametric Linkage was performed using Superlink v 1.6 program. Evidence of linkage was observed to markers at Xq23, DXS7133 and at Xq22.1 DXS101, with LOD score of 3.12 and 1.60, respectively. Identified locus in this study may carry a responsible gene in RSA. Narrowing down of this region may leads to identification of this gene Recurrent spontaneous abortion (RSA) is one of the most common health complications with a strong genetic component. Several genetic disorders were identified as etiological factors of hereditary X linked RSA. However, more genetic factors remain to be identified.

Autosomal Recessive Non-syndromic Hearing Loss (ARNSHL)، in up to 50 percent of the cases، is caused by mutations in GJB2 (GJ: Gap Junction) gene، encoding connexin 26. However 10 to 42 percent of patients with recessive mutations are carriers of only one mutant GJB2 allele. Mutations in GJB4 gene encoding Cx30. 3 can also lead to hearing loss. Mixing of different connexins in heteromeric and heterotypic GJ assemblies is possible. The aim of this study is to answer whether variations GJB4 gene can be the second mutant allele causing the disease in Digenic mode of inheritance in the GJB2 heterozygous cases studied.

In this descriptive study 42 subjects with ARNSHL from seven provinces of Iran were examined and using polymerase chain reaction (PCR) then conservation of involved amino acids was obtained. According to the variations found in patients، 200 hearing control samples were tested sequenced using Restriction Fragment Length Polymorphism (PCR-RFLP) method.

In GJB4 gene five heterozygous variations (c. 451C>A، c. 219C>T، c. 507C>G، c. 155_158delTCTG، c. 542C>T) were found in five patients and 13 control individuals. c. 542C>T variation was not detected in control samples and conservation score of corresponding amino acid was very high. Conclution: Regarding the obtained evidences، it is suggested that c. 542C>T variation in GJB4 and other variations in this gene with lower possibility might contribute to ARNSHL in digenic pattern in heterozygote carriers of GJB2.