They showed that IgG antibody to beta 2 microglobulin was found in 68% of 22 patients with AS, although the presence of IgG anti-beta2 microglobulin was 71% in 35 SLE patients, the level of anti-beta2 microglobulin in AS patients was highest in all groups (20). The gene discussed is B2M; the disease is systemic lupus erythematosus.