Mutations involved in inflammatory bowel disease (IBD) development include genes that regulate immune activation and the subsequent response, such as IL12B, IL2, IFNG, IL10, TNFSF8, TNFSF15, IL7R, DENND1B, JAK2 and those that also regulate ER stress, glucose, bile salt transfer and organic ion transporter, including XBP1, SLC9A4, SLC22A5 and SCL11A1, as shown in Figure 1 [26]. The gene discussed is JAK2; the disease is inflammatory bowel disease.