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Association of a novel SNP in the ASIP gene with skin color in black-bone chicken.
Yu S, et al.
Anim Genet. 2019.
(abstract) https://www.ncbi.nlm.nih.gov/m/pubmed/30883845/
Figure S1 Skin color of slaughtered hens. Hens with white and black skin.
Fig1-PDF

In this study of a Chinese chicken breed (Dongxiang, blue eggshell layer) with separate populations segregating Fm and fm+ they found a correlation between Fm and lower laying production in comparison to the related fm+ segregated (ie Fm allele had a pleiotropic effect on egg laying).

Genomic Analysis Reveals Pleiotropic Alleles at EDN3 and BMP7 Involved in Chicken Comb Color and Egg Production.
Dong X, Li J, Zhang Y, Han D, Hua G, Wang J, Deng X, Wu C.
Front Genet. 2019 Jun 28;10:612.
doi: 10.3389/fgene.2019.00612. PMID: 31316551; PMCID: PMC6611142.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6611142/