TNFRSF1A and inflammatory bowel disease: The included studies represented a wide range of polymorphisms that could influence biological treatment in IBD, such as in TNF-α and TNFR1/2 genes (n = 15), in innate immunity related genes (n = 9), in apoptosis and autophagy genes (n = 4), and in PTPN2 gene (n = 2).