The frequenc 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 deh1ive 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 97.8of 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.