Besides, circulating Nrg4 levels are lower in individuals with obesity (Cai et al., 2016; Guo et al., 2021), MASLD (Dai et al., 2015; Tutunchi et al., 2021; Wang et al., 2019a), and T2DM (Zhang et al., 2017), compared to healthy controls. The gene discussed is NRG4; the disease is obesity due to melanocortin 4 receptor deficiency.