Association of pigmentation and melanocortin-one receptor genotype with susceptibility to noise-induced hearing loss in college-aged music students

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Charles Brian Pudrith (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Susan Phillips

Abstract: Approximately 13% of the American population between the ages of 20-69 have signs of noise-induced hearing loss. Noise exposure at least partially causes hearing loss by generating free radicals in the ear, which damage cells. Eumelanin is an antioxidant that scavenges the free radicals and may protect the ear from noise-induced damage. Eumelanin is also a polymer that depicts hair and eye color and sensitivity to sunlight. Production of eumelanin is partially regulated by the gene, melanocortin-one receptor; individuals with single nucleotide polymorphisms in this gene have reduced eumelanin expression. The purpose of this study was to measure the extent to which pigmentation, e.g. hair and eye color and sunlight sensitivity, is associated with noise-induced hearing loss, and measure the extent to which single nucleotide polymorphisms in the melanocortin-one receptor gene are associated with noise-induced hearing loss. To accomplish this goal, we used a phased approach design and first evaluated hearing loss and pigmentation in 155 student musicians. This data was used to measure the association of pigmentation and noise-induced hearing loss. Then, buccal cells were collected in 111 student musicians with low to moderate levels of sunlight sensitivity so that we could measure single nucleotide polymorphisms in the melanocortin-one receptor gene. According to two multifactor analyses of variance, no association was found between noise-induced hearing loss and pigmentation (F(82,72) = 0.707, p = 0.936), nor melanocortin-one receptor genotype (F(79,39) = 0.488, p = 0.996). Despite our statistically insignificant results, we were able to detect a trend of increased thresholds in individuals with pigmentation indicating decreased levels of eumelanin. Also, one single nucleotide polymorphism, rs2228479, did show enough of an association with noise-induced hearing loss to warrant further investigation. Our inability to detect significant effects may have been due to an unexpected decrease in audiometric thresholds compared to previous measurements in this population. In this study, we used ER-3A inserts to evaluate hearing, which are more reliable for measuring thresholds between 4000 and 8000 Hz compare to TDH-39’s, which were used in previous analyses. It is also possible that we would have detected a stronger association of melanocortin-one receptor genotype and noise-induced hearing loss if we had sequenced the entire gene. Therefore, further research is required to evaluate the effects of noise exposure on student musicians using more sensitive audiometric criteria. Also, the association of melanocortin-one receptor genotype and noise-induced hearing loss should be evaluated with the entire melanocortin-one receptor sequence.

Additional Information

Language: English
Date: 2017
Melanin, Melanocortin-one receptor, Noise-induced hearing loss, Pigmentation
Deafness, Noise induced
MSH (Hormone) $x Receptors
College Students $x Health and hygiene
Music students $x Health and hygiene
Musicians $x Health and hygiene

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