RYR1 and Malignant hyperthermia: In pigs, balancing selection at c.C1843T mutation in the ryanodine receptor 1 (RYR1) gene [13, 14] is likely to have caused an increase in incidence of porcine stress syndrome (also known as malignant hyperthermia) in the 1970s and 1980s, due to the association of the causative missense mutation with reduced backfat–a trait under selection.