Associations between the c-myc proto-oncogene and carcass quality traits in the pig: evidence for epistasis with the Ryr1-gene

c-myc is an ubiquitous nuclear phosphoprotein involved in the regulation of cell-growth, differentiation and apoptosis. Higher nuclear levels of c-myc block adipogenesis and trigger the onset of myogenesis and folliculogenesis. The c-myc proto-oncogene has the potential of a mediator between second messengers such as calcium and cAMP and gene expression. As both are involved in stress-susceptibility and carcass quality in the pig, this study investigates associations between c-myc genotypes and carcass quality traits as well as interactions with the Ryr1 genotype in this species. An association between c-myc and carcass fat traits was evident, but did not reach genome-wide significance levels. Significance niveaus, explained variance and mean differences between the homozygotes of the Ryr1-gene which clearly decreased from the AA-genotype to the BB-genotype of c-myc are indicating a gene interaction between both genes. Mean differences in lean percentage (expressed in SD) decreased by 89.2% in ME × PI and by 86.3% in WS × PI. The existing but weakly developed significances of the association between c-myc and carcass fat traits are discussed under the aspect of epistatic nullification.