Loss of KDM4B in mice results in increased fat mass and increased expression levels of lipogenesis-related genes, thereby leading to obesity associated with reduced energy expenditure and impaired adaptive thermogenesis, which is often accompanied by hyperlipidemia, insulin resistance, and liver and pancreas pathology (Cheng et al., 2018; Kang et al., 2018). The gene discussed is KDM4B; the disease is obesity due to melanocortin 4 receptor deficiency.