SNaPshot based genotyping of the RYR1 mutation in Portuguese breeds of pigs

The porcine stress syndrome or malignant hyperthermia is an inherited autosomic recessive disease, which results in neuromuscular disorders leading to death in homozygous individuals and is associated with deterioration of meat quality. The defect in susceptible animals results from modifications in the calcium release channel or Ryanodine Receptor (RYR1), with a mutation leading to a C to T transition in nucleotide 1843 of the gene. The objective of this work was to develop a method based on analysis of SNPs to detect the mutation described in the RYR1 locus in pigs, and study polymorphisms of the gene in four exotic (Large White, Landrace, Duroc and Pietrain) and three native (Bísaro, Alentejano and Malhado de Alcobaça) breeds of pigs in Portugal. The method was successful in identifying the mutation by analysis of SNPs, and results indicate a high incidence of the mutant allele in Pietrain (0.75) and, to a lesser degree, in Malhado de Alcobaça (0.34) and Landrace (0.28); frequencies in Alentejano, Bísaro and Large White ranged between 0.04 and 0.09. These results suggest the need to establish breeding programs aimed at eliminating the susceptibility allele from those populations.