DETECTION OF THE RYANODINE RECEPTOR MUTATION ASSOCIATED WITH MALIGNANT HYPERTHERMIA IN PUREBRED SWINE POPULATIONS

A restriction endonuclease assay (REA) that reveals a C/T transition i n the ryanodine receptor gene (ryr-1 locus) was proposed to test swine for malignant hyperthermia. The REA was tested in a heterologous pig population of 1,227 individuals representing Hampshire, Duroc, Landrac e, and Yorkshire breeds. Of this group, 713 pigs had been classified o n the basis of the halothane challenge and progeny testing into the th ree possible Hal genotypes (685 negatives, 24 carriers, and 4 suscepti bles). The REA confirmed the four susceptibles as T/T, 17/24 carriers as C/T, and 659/685 negatives as C/C. The rest of the sample was const ituted of 514 pigs that had not been selected on the basis of the halo thane gene. The proportions of C/T and T/T pigs within the breeds repr esented were 3.2 and 1.6% for Duroc, 27.3 and 1.4% for Landrace, and 1 7.9 and 1.9% for Yorkshire. No T/T allelic pairs were found in the Ham pshire breed, although the sample was very small. Genotypic distributi on and allelic frequencies at the ryr-1, Phi, and Pgd loci were report ed among the breeds.