Interferons (IFNs) are an essential family of immunostimulatory cytokines, classified broadly into three subtypes: type I (IFN-α, β, ε, κ and ω), type II (IFN-γ), and the recently defined type III (IFN-λ) [89], among which INF-γ has been extensively studied in IBD. This evidence concerns the gene IFNA1 and inflammatory bowel disease.