The circadian clock is dysregulated by obesity (Kohsaka et al., 2007; Xu et al., 2014), and recent studies suggest that liver leukocyte recruitment and migration show a circadian rhythm (Scheiermann et al., 2012; Solt et al., 2012) whose alteration can result in steatosis (Solt et al., 2012; Xu et al., 2014). The gene discussed is CLOCK; the disease is obesity due to melanocortin 4 receptor deficiency.