Human Melanopsin (OPN4) Gene Polymorphisms: A Systematic Review.

Abstract

Melanopsin (OPN4) gene is crucial in non-visual processes, and certain variants of this gene, single nucleotide polymorphisms (SNPs) have been linked to altered light sensitivity and physiological responses. Those may have an impact on health, such as photoentrainment, circadian rhythms, insomnia, seasonal affective disorder (SAD) and potentially increase susceptibility to mental disorders and metabolic problems. This research reviews the effects of OPN4 on retinal and extraocular tissues, that suggests a systemic effect of light exposure. The aim of this systematic review is to explore the current literature regarding OPN4 gene and its SNPs, along with its associations to health related problems. We searched using PubMed and ScienceDirect databases with terms related to OPN4 and SNPs in humans. The publications were from January 1998 to August 2024. We identified 734 studies, and after screening titles, abstracts, and exclusion criteria, 9 studies were included in the review. The review was done following the PRISMA guidelines and conducted by two independent reviewers. Our review revealed the existing SNPs of the OPN4 gene along with its current associations. Some of the SNPs were more studied, such as P10L and I394T. However, the current information doesn’t mention any specific mechanism by which could change the OPN4 function. We found that very few human OPN4 SNPs have been explored and that their associations have a potential effect in multiple health related areas. For future research, it is recommended to explore identified SNPs with alternative associations related to OPN4 functions.