GPT and fatty liver disease: However, loss of Slc39a5 resulted in sex-specific differences in most NAFLD-related traits, with females benefiting more significantly compared to males, displaying significant reductions in hepatic steatosis (Figure 4G), serum ALT (but not AST) (Figure 4I and J), NAFLD activity score (Figure 4K), and hepatic fatty acid synthase levels (Figure 3—figure supplement 3B–D), and a significant elevation in hepatic and serum beta-hydroxybutyrate levels (Figure 4L and Figure 3—figure supplement 6).