Gene-Polymorphism in Non - Syndromic Hearing Loss: A Systematic Review.

Hearing loss that happens alone, without other related physical or developmental issues, is known as non-syndromic hearing loss (NSHL). About 70% of instances of hereditary hearing impairment are of this kind, making it the most prevalent type of genetic hearing loss. There are three possible inheritance patterns for the condition: autosomal dominant, autosomal recessive, and X-linked. The most common type is autosomal recessive. Studies have shown a large number of genes implicated in the auditory system, and genetic variables are important in the development of NSHL. These comprise genes encoding elements of the central auditory circuits, auditory nerve, and cochlea. Hearing loss can result from a number of mutations or polymorphisms (differences in the DNA sequence) in various genes, ranging from mild to profound. Thus several studies showing different gene involved, a systematic review is needed. Two databases PubMed (medicine) and Google scholar, as the main literature source and performed literature searches using relatively mature search formula. Based on the inclusion and exclusion criteria, after screening 150 articles, 12 articles were selected and reviewd for the study. The results demonstrate that NSHL is largely caused by genetic alterations, with some polymorphisms being more common in particular populations. For instance, GJB2-related mutations are uncommon in sub-Saharan Africa, where other genetic variables probably prevail, but they are noticeably widespread in Asian and Caucasian populations.