Association of rs1426654 genotypes with melanin index. (A) Distribution of melanin index (MI) in 1228 individuals of Cohort A. The two dotted black lines represent approximately 10% thresholds for the low (MI<38) and high (MI>50) MI groups, which were used to assess genotype-phenotype association using a logistic regression model. (B) Distribution of mean melanin index for the genotypes of rs1426654. The mean melanin indices for each genotype, as obtained separetely for males and females are shown together with their 95% confidence intervals, as estimated by multiple imputation model.