question: Which diseases have been associated with the PTPN22 620W allele?
answer: The functional polymorphism 620W in the intracellular tyrosine phosphatase PTPN22 gene has been shown to confer susceptibility to the development of type 1 diabetes, seropositive rheumatoid arthritis, systemic lupus erythematosus, Hashimoto thyroiditis, and Wegener's granulomatosis (granulomatosis with polyangiitis).