RGS2 and autoimmune pancreatitis: The risk of AIP increases depending on the minor allele of some SNPs and haplotypes of the candidate genes regulating G-protein signaling, including the RGS2 gene (regulator of G-protein signaling 2); the ADORA1 gene (adenosine A1 receptor); and the ADORA2A (adenosine A2A receptor) and ADORA3 (adenosine A3 receptor) genes.