USE OF A DNA-BASED TEST FOR THE MUTATION ASSOCIATED WITH PORCINE STRESS SYNDROME (MALIGNANT HYPERTHERMIA) IN 10,000 BREEDING SWINE

To test the hypothesis that the mutation associated with porcine stres s syndrome (PSS, malignant hyperthermia) was present in a large propor tion of North American and English swine, a simple and rapid laborator y protocol was used for cost-effective, large-scale diagnosis of susce ptibility to Pss. This Pss test was applied to 10,245 breeding swine o f various breeds from 129 farms in the United States, Canada, and Engl and. Approximately 1 of 5 swine was a heterozygous carrier of the Pss mutation, with approximately 1% being homozygotes. Prevalence of the P ss mutation was 97% for 58 Pietrain, 35% for 1,962 Landrace, 15% for 7 18 Duroc, 19% for 720 Large White, 14% for 496 Hampshire, 19%for 1, 72 7 Yorkshire, and 16%for 3,446 crossbred swine. The Pss gene frequencie s for these breeds were 0. 72, 0.1 9, 0.08, 0.10, 0.07, 0.10, and 0.09 , respectively. In addition to these breeds, we have identified the PS S mutation in Poland China and Berkshire breeds. These gene frequencie s were 30 to 75% lower in Canadian swine than in US swine, with the ex ception of Yorkshires, for which the gene frequency was threefold high er in Canadian swine. English swine were similarly, or more so, affect ed than were US swine. Accuracy was estimated at > 99%. Cost to perfor m the test was < $201 animal. Depending on the perceived net balance o f deleterious and beneficial effects of the mutation, the Pss test cou ld be used to eradicate the PSs mutation from herds, or for controlled expression of the mutation.