Plumage color is an artificially and naturally selected trait in domestic ducks. Black, white, and spotty are the main feather colors in domestic ducks. Previous studies have shown that black plumage color is caused by MC1R, and white plumage color is caused by MITF. We performed a genome-wide association study (GWAS) to identify candidate genes associated with white, black, and spotty plumage in ducks. Two non-synonymous SNPs in MC1R (c.52G>A and c.376G>A) were significantly related to duck black plumage, and three SNPs in MITF (chr13:15411658A>G, chr13:15412570T>C and chr13:15412592C>G) were associated with white plumage. Additionally, we also identified the epistatic interactions between causing loci. Some ducks with white plumage carry the c.52G>A and c.376G>A in MC1R, which also compensated for black and spotty plumage color phenotypes, suggesting that MC1R and MITF have an epistatic effect. The MITF locus was supposed to be an upstream gene to MC1R underlying the white, black, and spotty colors. Although the specific mechanism remains to be further clarified, these findings support the importance of epistasis in plumage color variation in ducks.

Parkinson\'s disease (PD, OMIM 168600) is a neurodegenerative disorder featured by degeneration of melanin-positive dopaminergic neurons. Epidemiologic studies have suggested that PD and malignant melanoma (MM) might share common genetic components. Recently, the p.R160W variant in the melanocortin 1 receptor gene (MC1R, OMIM 155555), a risk factor for MM, has been identified to be associated with PD in Spanish population. To explore whether the MC1R variants are associated with sporadic PD in Chinese population, we designed a case-control comparison study and studied three variants, including rs3212366 (p.F196L), rs33932559 (p.I120T) and rs34090186 (p.R67Q), in the MC1R gene in 512 Chinese Han patients with sporadic PD and 512 age, gender and ethnicity matched normal controls. For rs3212366, only the TT genotype was identified in both PD and control cohorts. For variants rs33932559 and rs34090186, we did not identify any statistically significant difference in either genotypic distribution or allelic distribution between the PD cohort and control cohort, and in addition, we did not identify any related haplotype that would either increase the risk for PD or play a protective role against PD. Our data suggest that none of the three variants of the MC1R gene and related haplotypes be associated with sporadic form of PD in Chinese Han population from Mainland China.