Second, our use of the revised more stringent guidelines for defining normal ALT may have increased the prevalence of an elevated ALT; however, we considered that this definition was appropriate given that previous studies showed ALT levels are lower in co-infection even in the setting of liver disease [6] and that they are the currently accepted normal levels of ALT in patients with HBV mono-infection [AASLD guidelines [48]]. This evidence concerns the gene GPT and liver disorder.