CCR6 and rheumatoid arthritis: CCR6 are also involved in several autoimmune diseases, including psoriasis and RA [96–98]; however, CCR6 polymorphisms have not been associated with AS in the few populations that have been analyzed [98, 99], despite the fact that some studies have demonstrated that it is expressed on the Th17 cells of AS patients [100, 101] and that these patients have a higher proportion of these cells [43].