Pedigree patterns of families having at least one member with sensorineural deafness in Hamadan.

Sensorineural hearing loss is a relatively common disorder that causes different degrees of reduction in voice perception and speech recognition. Its incidence is 1 in a 1000 neonate of which 50% is the result of genetic factors. About 80% of the hereditary deafness cases are non-syndromic and are inherited in an autosomal recessive mode. Recent studies show that mutation in the connexin 26 gene (GJB2) on chromosome 13 is associated with autosomal recessive non-syndromic hearing loss (ARNSHL) in many populations. So study of pedigree patterns of families having at least one member affected with hearing loss will hand a valuable information about its etiology and also its mode of inheritance. The results will make us able to help such families in genetic counseling procedure and in determining the high-risk cases. Also it will be a good point for starting molecular study to identify the related mutant gene/s. This descriptive and analytical study was performed on all families (N=30) that had at least one member with ARNSHL studying in Baghcheban Center, Hamadan, Iran. Data was obtained from files of the affected cases, then the suitable questionnaires were filled after face to face interviews with their parents. The cases were indicated as deaf if they had hearing loss more than 40db. Then based on the results of the interviews, their pedigrees were drawn and based on the standard criteria, the pattern of inheritance was determined. By employing the descriptive statistics, the results were evaluated and analyzed. Finally the results were compared with others and the role of consanguinity and genetic isolation in occurrence of hearing loss was studied. The results showed that pedigree patterns in all families interviewed were autosomal recessive. 90% of parents had consanguineous marriages and half of the families were related to the isolate groups.