The Impact of Pigmentation on Hereditary Hearing Loss

Hereditary hearing loss affects millions worldwide and exhibits significant variability in severity among individuals with identical genetic mutations. Recent research highlights that factors beyond the primary genetic defect influence disease progression, with pigmentation emerging as a key component.

Melanin, the pigment responsible for skin, hair, and eye color, may play a dual role in inner ear health—offering protection under certain conditions or contributing to pathology under others. Scientists from Japan, led by Junior Associate Professor Taku Ito at the Institute of Science Tokyo, investigated how pigmentation impacts hearing loss using genetically engineered mice lacking the SLC26A4 gene, which is associated with hereditary hearing deficits.

Their study, published in Neurobiology of Disease, showed that melanin's role varies depending on genetic context. Comparing pigmented and non-pigmented mice, researchers observed that pigmented mice experienced more severe hearing impairment and had larger, more active macrophages, immune cells that mediate inflammation. Notably, the accumulation of melanin was linked to impaired degradation rather than increased production, leading to metabolic stress and immune activation.

This accumulation appears to trigger a chronic inflammatory response that exacerbates hearing deterioration, especially in pigmented individuals. Conversely, non-pigmented mice showed less immune activation and milder hearing loss. These findings reveal that melanin's influence on inner ear health is complex and context-dependent, acting as both a protector and a pathological factor.

The study suggests that pigmentation status could serve as a biomarker for predicting disease severity and guiding personalized treatment approaches. Therapies aimed at modulating melanin degradation pathways or immune responses might hold promise for preventing or slowing hereditary hearing loss. Furthermore, understanding these mechanisms may help explain differences in susceptibility among different ethnic groups.

Overall, this research advances our understanding of the intricate relationship between pigmentation and auditory health, paving the way for targeted interventions in hereditary hearing disorders.

Source: https://medicalxpress.com/news/2025-07-role-pigmentation-hereditary-loss.html