IRGM and Crohn disease: Genetic mutations in the Immunity‐related GTPase M (IRGM) gene or promoter are suggested to increase susceptibility to several inflammatory and infectious diseases including Crohn's disease, tuberculosis, sepsis, and ankylosing spondylitis (Massey & Parkes, 2007; Parkes et al, 2007; Intemann et al, 2009; Lu et al, 2013; Kimura et al, 2014; Lin et al, 2016; Xia et al, 2017; Yao et al, 2018).