The 193 dogs with liver disease or injury (66 diagnosed, 127 based on elevated AST values) showed a similarly strong association between ALT activity and the GPT locus (22% and 43% reduction in heterozygous and homozygous dogs, respectively), with a greater proportion of homozygous dogs with liver injury having ALT activity within the reference interval compared to heterozygous or wildtype dogs (Fig 2B, Table 2). Here, GPT is linked to liver disorder.