Contribution of GJB2 gene mutations to hearing loss in Pakistani population – A Narrative Review

Pakistan has a unique population for the study of recessive genetic diseases due to a higher consanguinity rate. Hearing impairment is the loss of hearing normal sounds, and it is a common sensory disorder that affects more than 466 million people worldwide. Immuno-genetic and other environmental factors like loud noises, drug usage, and viral infections are the causes of hearing loss. Hearing loss is categorized into a syndromic hearing loss (70%) and non-syndromic hearing loss (30%). GJB2 mutations are one of the main causes of hearing loss in different populations, including Pakistan. The GJB2 gene encodes a gap junction protein involved in the homeostasis of the inner ear through the recycling of potassium ions. The prevalence of GJB2 mutation in the Pakistani population varies from 6.1 to 9.2%. The most common mutations found in the Pakistani population are 71G>A (p.(Trp24*), 231G > A (p. Trp77*), c.35delG (p. Gly11Leufs24*),c.355G>T (p. Glu119*) 457G > A (p.Val153Ile), 598G > A (p.Gly200Arg), 439G > A (p.Glu147Lys), c.377_378insATGCGGA (p.Arg127Cysfs*85). c.1055C>T (p. Pro352Leu), c.6202A>C p.(Thr2068Pro), c.2496_2496delC p.(Tyr832*) and c.355G>T p.(Glu119*).Keywords: Gap junction protein, GJB2 mutations, Hearing loss