MICA and ankylosing spondylitis: MICA/B are highly polymorphic proteins, indeed more than 70 MICA and 30 MICB sequences have been described to date (Steven GE Marsh, Anthony Nolan Research Institute, http://hla.alleles.org/terms.html) and a number of diseases have been reported to be associated with MIC gene polymorphisms, including ankylosing spondylitis, Behçet’s disease, psoriasis, type I diabetes, and Addison’s disease (Stephens, 2001).