[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

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

Molecular pathology of 6 novel GJB2 allelic variants detected in familial and sporadic Iranian non syndromic hearing loss cases

Mutations of GJB2 gene encoding connexion 26 are the most common cause of hearing loss in many populations. A very wide spectrum of GJB2 gene mutations associated with hearing loss have been detected but pathogenic role has been tested only for a part of them. In this study, we have provided genetic evidence on the pathogenicity of our previously reported novel GJB2 allelic variants. The pathogenic role of GJB2 allelic variants were assessed using co segregation of each allelic variant with hearing loss in family members, absence of the allelic variants in control populations, coexistence with a second GJB2 mutation, nature of the amino acid substitution and evolutionary conservation of the appropriate amino acid. The GJB2 allelic variants including 363delC, 327delGGinsA, H16R and G200R have been co segregated with autosomal recessive non syndromic hearing loss in five families and are not found in control subjects. The G130V and K102Q were found in heterozygous state in two deaf individuals. G130V results in an exchange a residue highly conserved among all the connexins but was found with a rate of 1% in control subjects and K102Q results in an exchange a residue not conserved among all the connexins and not identified in control subjects. We conclude that, 363delC, 327delGGinsA, H16R and G200R may be pathogenic. However, the pathogenicity and inheritance of K102Q and G130V can not be assessed clearly and remains to be identified

[ effect of upper airway obstructive surgery on respiratory symtoms and Spo2]

The obstruction of the upper respiratory tract [URT] is one of the most important reasons patients' recurrent referral to the ENT clinic. Adentonsilar hypertrophy is almost common reason of the upper respiratory tract obstruction, and it will cause some changes in lung volumes and also in blood gases. The purpose of this study was to determine the effects of tonsillectomy on respiratory symptoms and arterial blood oxygen saturation. In a clinical trials study, in a pre and post operative manner, 62, 2-14 years old children were imposed to adentonsilectomy in an easy sampling way. The respiratory symptoms such as: snoring, dyspnea, feeling airway obstruction, mouth breathing and oxygen saturated hemogolobin condition [Spo2], prior to surgery and one month after operation, has been studied and recorded. The results were compared with paired t-test. In a preoperative manner, 80% of patients had mouth breathing symptom and mouth dryness which were reduced to 10% after surgery. Spo2 measurement had no significant difference before and after surgery, and, it was in a normal range. The correction of respiratory obstruction due to adenotonsilar hypertrophy does not make any changes in arterial blood oxygen. The surgery which is used for correction of these obstruction, will just improve the clinical respiratory symptoms such as snoring and mouth breathing