Furthermore, the drug-induced lymphocyte stimulation test (DLST) was positive in only 25% of UC patients intolerant to 5-ASA.29 In contrast, a recent GWAS has shown that a candidate SNP in rs144384547 in regions of the regulator of G-protein signaling 17 (RGS17) gene on chromosome 6 was associated with 5-ASA-induced fever and diarrhea in patients with IBD. Here, RGS17 is linked to inflammatory bowel disease.