Preliminary Association Study of SNPs in MFN2 Gene Showing Marbling-Associated Expression Changes

Researchers have previously showed that the mitofusin 2 (MFN2) gene involved in energy balance through mitochondrial fusion and expressed in slow-twitch oxidative fiber that is observed in high-marbled muscle, possesses expression differences in musculus longissimus muscle between low-marbled Holstein and high-marbled Japanese Black steer groups. In the present study, researchers found that a marker (IDVGA-49) close to the MFN2 was polymorphic between low-marbled Holstein and high-marbled Japanese Black steer groups and exhibited significantly different allelic distribution between Japanese Black sires with extremely high predicted breeding value for marbling and with extremely low one. Further, researchers detected Single Nucleotide Polymorphism (SNP) in the MFN2 gene between low-marbled Holstein and high-marbled Japanese Black steer groups. The allelic distributions of the 6 SNPs in the MFN2 were indistinguishable between Japanese Black sires with extremely high predicted breeding value for marbling and with extremely low one. The findings suggest that an unidentified true causal mutation which is in linkage disequilibrium with the IDVGA-49 marker but not the 6 SNPs may be related to changes in MFN2 gene expression and/or marbling. The IDVGA-49 marker may be useful for effective marker-assisted selection to increase the levels of marbling.