Contrarily to serum Nrg4 levels, a cross-sectional study by de Muncket al., 2021 determined the levels of Nrg4 in the plasma and its association with fatty liver disease severity, where it was found that Nrg4 levels were not significantly different between NAFLD subjects with or without hepatic fibrosis [52]. Here, NRG4 is linked to fatty liver disease.