A switch-variant model integrates the functions of an autoimmune variant of the phosphatase PTPN22

The R620W polymorphism in protein tyrosine phosphatase nonreceptor type 22 (PTPN22) predisposes carriers to several autoimmune diseases. Two papers in Science Immunology and Science Signaling on this human disease-associated variant lead us to propose a new switch-of-function model.