Hereditary hearing loss. Genetic factors in ethiopathogenesis of deafness

Abstract

Congenital hearing loss is one of the most common defects diagnosed 1 in 1000 newborns. Prelingual hearing loss disturbs development of the child and it is one of disabling conditions in present day environment. It is a highly heterogeneous disorder, with the majority of cases having genetic etiology. Ear is a very complex organ, proper development of the tissues in macroscopic, microscopic and molecular levels and function are essencial for the perception of sound. These processes are influenced mostly by genetic factors. Recent advances in the gene identification techniques have revolutionized the clinical approach to congenital hearing loss. More than 400 and 100 genetic loci are associated with syndromic and nonsyndromic hearing loss respectively. High heterogeneity of hearing loss is important in genetic counselling – the disorder may be inherited in autosomal dominant, autosomal recessive, X recessive and mitochondrial manner. In this review we discuss the structure and the function of auditory organ, the pathogenic mechanisms of hearing loss and provide the clinical approach. The identification of genes implicated in pathogenesis of hearing loss is essential in establishing of genetic diagnosis and rehabilitation, opens new perspectives in treatment, and allows predicting the severity of the disorder, progression and effectiveness of rehabilitating measures.