A genome-wide epistatic network underlies the molecular architecture of continuous color variation of body extremities
Résumé
Deciphering the molecular architecture of coat coloration for a better understanding of the biological mechanisms underlying pigmentation still remains a challenge. We took advantage of a rabbit French experimental population in which both a pattern and a gradient of coloration from white to brown segregated within the himalayan phenotype. The whole experimental design was genotyped using the high density Affymetrix® AxiomOrcun™ SNP Array and phenotyped into 6 different groups ordered from the lighter to the darker. Genome-wide association analyses pinpointed an oligogenic determinism, under recessive and additive inheritance, involving genes already known in melanogenesis (ASIP, KIT, MC1R, TYR), and likely processed pseudogenes linked to ribosomal function, RPS20 and RPS14. We also identified (i) gene-gene interactions through ASIP:MC1R affecting light cream/beige phenotypes while KIT:RPS responsible of dark chocolate/brown colors and (ii) a genome-wide epistatic network involving several others coloration genes such as POT1 or HPS5. Finally, we determined the recessive inheritance of the English spotting phenotype likely involving a copy number variation affecting at least the end of the coding sequence of the KIT gene. Our analyses of coloration as a continuous trait allowed us to go beyond much of the established knowledge through the detection of additional genes and gene-gene interactions that may contribute to the molecular architecture of the coloration phenotype.
Mots clés
Coat coloration
Copy number variation
epistasis
Melanogenesis
Recessivity
Coat coloration Copy number variation
epistasis Melanogenesis Recessivity BAF
B allele frequency
CNV
copy number variation
CS
credible set
GWAS
genome wide association study
LD
linkage disequilibrium
LFSR
local false sign rate
LRR
log R ratio
Ocu
Oryctolagus cuniculus
PIP
posterior inclusion probability
SNP
single nucleotide polymorphism
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