Hereditary and Non-hereditary Pattern of Deafness in Golestan Province, Iran

Hearing impairment as a heterogeneous disorder is the most common sensory defect. Genetic (hereditary) hearing loss involves 50% of total cases and the remaining 50% are non-hereditary cases caused by unknown causes. This study aimed to investigate the role of consanguineous marriage and the relationship between the type of deafness and the hereditary pattern in families with more than one deaf patient in Golestan province, Iran.

The study population included 165 families with deaf members whose files were available in the General Welfare Department of Golestan Province. They were randomly selected during 2018-2019. Data, including number of family members with hearing loss and severity of the condition were collected by face-to-face interviews with parents. Data analysis was done in SPSS.

The mean age of the subjects was 27.67±9.71. Female and male cases included 42.1% and 57.9%, respectively. In 85% of the cases, genetic factor and in 15% acquired factors were responsible for hearing loss. Among the genetic causes, 90.9% of the population were autosomal recessive and 9.1% were autosomal dominant. Moreover, 70% of families had consanguineous marriage and first-degree family relationship was seen in 92 families (80%).

Genetic factor with the autosomal recessive inheritance pattern was the most common cause of hearing loss in the population studied. Increasing awareness about the consequences of consanguineous marriage and genetic counseling are indispensable in decreasing the rate of this condition.