Association of melanogenesis genes with skin color variation among Japanese females

Background: Skin color mainly reflects pigmentation resulting from melanin. Although many of the detailed molecular mechanisms involved in melanin pigmentation are being revealed, little is understood about the genetic components responsible for variations in skin color within or between human populations. Objective: To investigate the contribution of the melanogenesis genes to skin color variation in Japanese population. Methods: We examined the association between 12 variants of four pigmentation-related genes (TYR, OCA2, SLC45A2, MC1R) and variations in the melanin index of 456 Japanese females using a multiple regression analysis. Results: OCA2 A481 T (p = 6.18 x 10(-8)) and, OCA2 H61 5R (p = 5.72 x 10(-6)) were strongly associated with the melanin index. In addition, our results yielded evidence for a significant association in a combined analysis of males and females (OCA2 A481T p = 2.1 x 10(-11), and OCA2 H615R p = 1.0 x 10(-7)). Then five surviving variants including A481T, H615R, T387M in OCA2, D125Y in TYR, and T500P in SLC45A2, accounted for contribution to about 11% of the melanin index. Conclusion: The skin color analysis among Japanese was successfully carried out to determine the association with genetic components by using the melanin index as an objective indicator. We believe that a better understanding of the genetic basis of skin color variation will be valuable for elucidating the correlation of pigmentation phenotype with skin-cancer risk. (c) 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.