The finding that both IL-1 receptor (IL-1R) 1 and IL-1R2 are increased at a transcript level suggests a possible correlation with a genetic association between ERAP1 (ARTS1) polymorphisms and ankylosing spondylitis [20]; ERAP1 is a proteinase believed to lessen immune responses by cleaving receptors for cytokines including IL-1. This evidence concerns the gene ERAP1 and ankylosing spondylitis.