Genotypic and allelic frequencies of the melanocortin 1 receptor gene (MC1R) variant rs34090186 showed statistically significant differences in ET patients and controls (p = 0.027 and 0.028, odds ratio = 2.789 and 2.744, 95% confidence interval: 1.084–7.179 and 1.075–7.005). This evidence concerns the gene MC1R and essential thrombocythemia.