Surprisingly, mRNA levels of Nrg-4 in WAT are low in humans and mice with obesity (Wang et al., 2014; Comas et al., 2019), and in humans with metabolic syndrome (Guo et al., 2021; Cai et al., 2016) and obese children complicated by non-alcoholic fatty liver disease (NAFLD) (Wang et al., 2019). This evidence concerns the gene NRG4 and metabolic syndrome.