However, aberrant Th17 responses and IL-17A production have been implicated in a variety of autoimmune diseases and animal models, including rheumatoid arthritis (RA; Chabaud et al. 2000; Kirkham et al. 2006) and multiple sclerosis (MS; Matusevicius et al. 1999; Graber et al. 2008). This evidence concerns the gene IL17A and rheumatoid arthritis.