G6PD and obesity due to melanocortin 4 receptor deficiency: Moreover, given the importance of G6PD enzyme in glucose metabolism and its role in metabolic dysfunctions including diabetes, obesity and insulin resistance (Xu et al., 2005; Ham et al., 2013; Park et al., 2017; Wang et al., 2019), we can speculate that the virus-induced down-modulation of G6PD may contribute to the higher susceptibility to influenza virus infection in metabolic disorders (Hulme et al., 2017; Huo et al., 2017; Honce and Schultz-Cherry, 2019).