PCR GENOTYPING OF THE RYANODINE RECEPTOR GENE FOR A PUTATIVE CAUSAL MUTATION FOR MALIGNANT HYPERTHERMIA IN AUSTRALIAN PIGS

A total of 324 Australian pigs from two populations segregating for malignant hyperthermia (MH) were genotyped using a PCR/restriction endonuclease test for the 1843 C-to-T mutation in the skeletal muscle ryanodine receptor (ryr 1) gene, previously identified by FUJII et al. (1991) as the causal mutation for MH. Most of the pigs had also been halothane-tested, and in addition, some had been genotyped at linked biochemical markers. A comparison of error rates for the three testing methods revealed the PCR test to have a genotyping error rate of 2.5 %, compared with 2.8 % for linked biochemical markers, and an 11.1 % error rate for phenotypes defined by the halothane test. The results of the present study substantially extend the generality of the conclusions of FUJII et al. (1991) and OTSU et al. (1991), namely that the only causative MH mutation in ryr 1 is the C-to-T transition at nucleotide 1843. With the Australian and European populations tested in this study, this somewhat surprising findings is now consistent across many breeds and three countries, namely Canada, England and Australia.