[Study of three common mitochondrial mutations in Arab patients with nonsyndromic hearing loss in Khuzestan province, I.R.Iran]

Hearing Impairment [HI] is the most prevalent neurosensory disorder occurs in 1/1000 newborn. The majority of hearing deficiencies are of genetic origin. About%0-2 of the genetic HI cases are due to mutations in mitochondrial genes. In the present study we investigated the frequency of 3 mtDNA A1555G, A3243G and A7445G mutation of 62 patients with nonsyndromic hearing loss in Khuzestan province. In this descriptive study, we investigated the presence of three mitochondrial mutations; A1555G, A3243G and A7445G in 62 Arab subjects with autosomal recessive non syndromic hearing loss in Khuzestan province. DNA was extracted using standard phenol -chloroform method. The screening of the mitochondrial gene mutations was performed by PCR-RFLP procedure.The possible mutations were confirmed by direct sequencing. None of the investigated mutations; A1555G, A3243G and A7445G were detected in this study. However PCR-RFLP revealed two mutations; G3316A, A7445C in 2 deaf subjects studied. This study is shown that mtDNA mutations consist of G3316A and A7445C are responsible for few of ARNSHL in sample studied and none of the A1555G, A3243G and A7445G mutations are responsible for ARNSHL in this population. The data presented here will improve the genetic counseling of hearing impaired patients in Khuzestan province

[Screening of mitochondrial mutations of A1555G, A 3243G, and A7445G in MTRNR1, MTTL1 and MTTS1 genes in subjects with nonsyndromic sensorineural hearing loss]

Various frequencies of the mtDNA mutations have been reported from different population world wild. Three mitochondrial DNA [mtDNA] mutations including A1555G, A 3243G, and A7445G which occurred in MTRNR1, MTTL1 and MTTS1 genes were considered as the main causes of mitochondrial hearing loss in some populations. To determine the frequency of the A1555G, A3243G, and A7445G mutations in nonsyndromic sensorineural hearing loss subjects in Gilan. Forty six subjects with nonsyndromic sensorineural hearing loss were screened by provided questionnaire and audiogram from Gillan Welfare Organization. PCR-RFLP procedure was used in order to presence the MtDNA of A1555GA 3243G and A7445G mutations and was confirmed by subsequent direct sequencing. There was no MtDNA of A1555G, A3243G and A7445G mutation in the cohort study of 46 deaf individuals. Investigation of PCR-RFLP of the MTTL1 gene for existence A3243G mutation lead to identification a G3316A variant that destroyed other restriction site, in the other site of PCR fragment. Our finding indicated that possibility the association of mitochondrial mutations with deafness is very low in deaf subjects in north of Iran. According to existence the G3316A that its pathogenesis in relation to hearing loss phenotype has not stabilized, the frequency of G3316A is 1.46% that can be had highlights role of mitochondrial mutation in deafness

[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