A major locus (RN) affecting muscle glycogen content is located on pig chromosome 15.

The RN locus in pigs has a major effect on the amount of stored glycogen in white muscle and affects meat quality. The fully dominant RN- allele, associated with high glycogen content, occurs in the Hampshire breed. We have mapped the RN locus using a large half-sib family comprising one heterozygous RN-/rn+ Hampshire boar mated to homozygous rn+/rn+ Swedish Landrace x Swedish Yorkshire sows. The segregation at the RN locus was inferred from data on glycolytic potential and residual glycogen in white muscle which both showed clear bimodal distributions. Highly significant evidence for genetic linkage was obtained against microsatellite markers on Chromosome (Chr) 15. Multipoint analysis revealed the order Sw1111-8.0-S0088-10.6-RN-4.8-Sw936,Sw906 (recombination estimates are given as Kosambi cM). Comparative mapping data imply that the human homolog of RN is located on Chr 2q.