Myotonic pigs were all homozygous recessive for the deletion, whereas their progenitors were heterozygous, and all unrelated, non-myotonic pigs were homozygous “wild type.” A previous study investigating Hereditary Myotonia in cats associated the disease to the absence of exons 15 and 16 in the CLCN1 gene due to a defective donor splicing site21. This evidence concerns the gene CLCN1 and Myotonia.