Serum liver transaminase and ALP activities were increased amongst heavy khat users compared to nonusers (ALT: median 25 vs. 22 U/L, p=0.015; AST: median 32 vs. 26 U/L, p=0.003; ALP: median 92 vs. 77 U/L, p=0.003); however, by definition, none of the study participants presented with clinical signs of liver injury or recognized liver disease. This evidence concerns the gene GPT and liver disorder.