How is "Noise Induced Hearing Loss In The Left Ear" encoded by the genome?
Have you ever had an awesome night at a live concert only to realize you couldn’t hear that well when you left? This may only be a temporary loss of hearing if it is not too severe, but noise-induced hearing loss (NIHL) is a permanent hearing loss that slowly develops due to long-term exposure to hazardous sound levels. Many musicians or music students are at risk of this, given the nature of being exposed to hazardous sound levels. Although the heritability of NIHL can be difficult to determine, researchers have previously discovered that in combination with lifestyle and environmental factors, multiple genes may play a significant role in the eventual development of hearing loss.
Intense sound exposure can cause direct mechanical trauma and indirect metabolic distress in the inner ear (cochlea), damaging cochlear structures vital to hearing, such as hair cells and stereocilia bundles. Variants of several cochlear genes have been associated with susceptibility to NIHL in factory workers exposed to traumatic industrial noise, some of which are variants in ion transport proteins (KCNE1 and KCNQ4) and structural proteins (MYH14 and PCDH15). Although several studies have been carried out so far, the relationship between genetic variation and audiological measurement of NIHL in young adults largely remains elusive, possibly due to the varied NIHL definitions and headphones used for measuring hearing thresholds.
Researchers investigated the association between candidate genetic variants and audiometric measures of noise-induced hearing loss (NIHL) in 166 young musicians. Nineteen single nucleotide polymorphisms (SNPs) in 13 cochlear genes previously reported to be related to NIHL in factory workers were examined. Averaging hearing thresholds calculated the average hearing threshold (AHT) at 3000 and 4000 Hz for each ear. The results revealed a statistically significant association between rs667907 in the Myosin Heavy Chain 14 (MYH14) gene with DPOAE SNR in the left ear. In addition, the substitution of the C allele with the T allele of rs667907 had an additive effect in lowering inner ear abilities in study participants.
Although this study is limited to the SNPs previously associated with NIHL, considering the smaller sample size and lack of a replication sample, the researchers applied an additional scientific rigor by considering the positive association to NIHL for only those SNPs associated with DPOAE SNR in both
ears. They suggest readers and researchers use caution while considering SNPs associated with DPOAE SNR in only one ear. Read more about the study here:
https://pubmed.ncbi.nlm.nih.gov/32176153/
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