Sensorineural hearing loss (SNHL) occurs when the inner ear or nerve pathways from the inner ear to the brain are damaged. SNHL reduces the ability to hear even faint sounds. Most people with SNHS suffer from permanent hearing loss. It can result from illness, exposure to loud noise, malformations of the inner ear, head trauma, or drug abuse. However, most of the time sensorineural hearing loss results from genetic or hereditary factors. Rarely can SNHLS be medically or surgically corrected.
Sensorineural hearing loss primarily results from mutations in the GJB2 gene. In humans this gene encodes for gap junction beta-2 proteins (also known as connexin 26). Gap junctions are vital for several physiological processes. Along with the role they play in hearing; gap junctions also play an essential role in the depolarization of cardiac muscle, proper embryonic growth, and the conducted response by microvasculature’s. Mutations in connexin-encoding genes often lead to functional and developmental problems Mutations are changes in the nucleotide sequence of an organisms’ DNA. SNHL can be attributed to several types of mutations. Insertion and deletion are the most common mutations that lead to SNHL. Insertion occurs when one or more nucleotide pairs are added to a gene. Deletion is when there is a loss of one or more nucleotide pairs. The GJB2 has been studied in order to determine the best methods for intervention and prevention for sensorineural hearing loss. Many of these studies praise the benefits of genetic testing. Claiming it as the most beneficial method overall. Genetic testing can predict the absence or onset of a syndrome, including SNHL. Genetic testing could also reveal other clinical problems may not have been present at birth or early childhood, such as adolescent-onset blindness. Genetic testing provides a better understating of the genotype-phenotype correlations for clinical problems, including SNHL. This allows for direct and specific therapeutic interventions.
GJB2 is not the only gene associated with sensorineural hearing lost. However, there is little known about other genes that cause hearing loss. There are 45 known genes that contribute to SNHL. But there is little research on their relative contributions to causing SNHL. Molecular microarray technology is currently being used to find their relationship to the syndrome. Molecular microarray technology has allowed for DNA samples to be rapidly screened for thousands of possible genetic mutations. Microarray based screening is cost effective, and accurate. In comparison to alternative methods.
Previously sensorineural hearing loss was primarily screened for through radiographic evaluations. Which are a method of inspecting materials for hidden flaws by using the ability of short wavelength electromagnetic radiation (high energy photons) to penetrate various materials. Radiographic evaluations are used to diagnose temporal bone anomalies generally associated with Sensorineural hearing loss. These tests have been ditched by researchers due to their time consuming and expensive nature. Making the recent advancements in microarray technology a revolutionary development. But microarray technology is not problem free. Call rates among different microarray designs tend to vary considerably.
Obviously there is a need to further develop efficient methods for detection and prevention. Currently, adaptive methods of microarray technology and radiography evaluations are trying to accomplished this. Research developing new methods of detection and prevention will be continuing throughout the next several years. Hopefully the search will stay active, and new methods to screening and prevention of sensorineural hearing loss will arise.