Interestingly, PAPA syndrome (pyogenic sterile arthritis, pyoderma gangrenosum and acne) caused by mutations in the cytoskeletal adapter PSTPIP1 (which binds to WASp) shares cytoskeletal features with WAS and is also associated with overt IL-1β production54. This evidence concerns the gene PSTPIP1 and pyoderma gangrenosum.