[Molecular investigation of mtDNA A1555G, A3243G and A7445G mutations among the non syndromic hearing loss cases in Fars, Iran]

Hearing loss is a sensorineural disorder occuring in 1 out of 500 births. It happens due to some genetic/environmental causes or both. More than 60% of cases are noninherited and 80% non syndromic with autosomal recessive inheritance. In the present study we investigated the frequency of mtDNA A1555G, A3243 and A7445G mutations among the patients in Fars province. Seventy two non syndromic hearing loss subjects were studied. DNA was extracted using standard phenol-chloroform method. The screening of the mitochondrial gene mutations were performed using PCR-RFLP procedure. Finally, the possible mutations were confirmed by direct sequencing. None of the A1555G, A3243G and A7445G mutations was detected in this study. However, destroying a MTTL1 restriction site for the investigation of A3243G mutation, revealed a G3316A with allelic variant of 1.4% in the deaf subjects. Our data indicated that the mitochondrial A1555G, A3243 and A7445G mutations have no role in auditory deficits in patients studied

[DFNB59 gene mutations and its association with deafness in schoolchildren in kohgilooyeh and Boyerahmad province]

Hearing loss is a common disease affecting millions of people worldwide. Hearing loss can be caused due to genetic or environmental factors or even both. The genetic of hearing defect is highly heterogeneous and more than 100 genes are predicted to cause this disorder in humans. A newly identified gene [DFNB59] has been shown to cause deafness in some populations. Here we report mutation analysis for DFNB59 gene in 88 genetic non-syndromic hearing loss subjects. In this descriptive-lab based study which was conducted at the Cellular and Molecular Research Center of Shahrekord University of Medical Sciences, DNA was extracted from the peripheral blood samples using standard phenol chloroform procedure. Mutation analysis for DFNB59 gene was performed using PCR-SSCP/HA protocol. The suspected DFNB59 which was detected as shifted bands on PAGE were then confirmed by direct sequencing strategy. Two DFNB59 polymorphisms including c.793C>G and c.793C>T were detected in 8 and 1 deaf subjects respectively. We conclude that there is no association between DFNB59 mutations and deafness in the studied patients in the region

[DFNB59 gene mutations screening in non syndromic deaf subjects in Chaharmahal va Bakhtiari province]

The incidence of pre-lingual deafness is about 1 in 1000 neonates from which more than 60% of cases are inherited. Deafness is a heterogeneous disorder and may be due to genetic or environmental cause or both. Mutations in the DFNB59 gene encoding pejvakin protein has been very recently shown to cause neural deafness. In the present study, we have conducted type and frequency of the DFNB59 gene mutations in a cohort of 100 non syndromic deaf subjects in Chaharmahal va Bakhtiari province. In this descriptive-lab based study we investigated the frequency of DFNB59 gene mutations in the entire coding exons of the gene. DNA was extracted from the peripheral blood samples following the standard phenol chloroform procedure. DFNB59 gene mutations were investigated using PCR-SSCP/ Heteroduplex Analysis [HA]. The results of PCRSSCP/HA were confirmed by sequencing of exon 7, nested PCR and PCR-RFLP of 3 known DFNB59 mutations. Altogether 3 different gene polymorphisms [793C>G, 793C>T and 874G>A] and one mutation [988delG] were detected in 7, 5, 2 and 1 subjects respectively. Based on our data from the present study and previous study, we conclude that DFNB59 gene mutations have a very low contribution to deafness in patients in Chaharmahal va Bakhtiari province and are not of great clinical importance in this region

frequency of hearing loss etiology among deaf students in Chaharmahal va Bakhtiari province, Iran, 2008-2009

Hearing loss is the most common sensory disorder in human and has a profound economic and social impact in the modern world. The etiology of deafness can be due to genetic or non-genetic causes in origin. Genetics etiology of hearing loss is classified into syndromic and nonsyndromic. The aim of this study was to determine the etiology of deafness in deaf students in Chaharmahal va Bakhtiari province, Iran. Altogether, 265 patients with mild to profound hearing loss were contributed in this descriptive study. The subjects were deaf pupils from the schools of Chaharmahal va Bakhtiari province. Age of the students was between 6 and 22 years. Medical history, pedigree information and demographic data were collected using a questionnaire. Each patient underwent general and otoscopic examinations and also pure-tone audiometery. Otoacoustic emissions, as well as auditory brainstem response testing were performed in patients suspected to neural hearing loss. Consanguineous marriages were detected in 67.2% of deaf families, from which first cousins marriage was the most common with the rate of 78.1% of overall consanguinity. Our study revealed that up to 98.8% of genetic deafness cases were in autosomal recessive mode. We found sensorineural hearing loss as a predominant type of deafness in 97.8% of the population studied. Moreover, hearing loss with genetic in origin was found as the most frequent deafness etiology with a rate of 60.8% and then acquired and idiopathic hearing loss are in next step, respectively. We found syndromic etiology in 4.2% of the students and ophthalmic problems were the most dysfunction accompanied with hearing loss. This data highlight the importance of consanguine marriage in the studied population. We found a very high rate [67.2%] of consanguine marriage, which can be the main cause of congenital deafness