DRD4 and autoimmune pancreatitis: In this work, we analyzed 28 studies conducted from 1989 to 2021, studying 37 genetic variations, including SNVs/polymorphisms of four candidate dopamine receptor genes (DRD1, DRD2, DRD3, DRD4) involved in the development of AIP and AITD in patients with schizophrenia.