CYP2D6 and autoimmune pancreatitis: The Spanish study suggested that CYP genes may be penetrance modifiers in AIP because CYP2D6*4 and *5 are more frequent in LAIP than MAIP, despite the similar allele frequencies of CYP2D6*4 and *5 in the total AIP carriers and the general population (Menoyo et al., 2006), suggests CYP2D6*4 and *5 defective alleles play a protective role in the clinical onset of AIP, modulating the penetrance of AIP.