TNF and psoriasis: Sixteen case-control studies with a total of 2,253 psoriasis cases and 1,947 controls on TNF-α 308 G/A polymorphism [11-20,27-32] and fourteen studies on TNF-α 238 G/A polymorphism with 2,104 cases and 1,838 controls [11-17,19,28-33] were finally identified from three main databases, including Pubmed, Embase, and Web of Science.