PRB2 and autoimmune polyendocrinopathy: In a systematic review of 20 studies including 5992 patients, Radin et al reported that a median of 55% of patients with confirmed APS were IgG anti-PS-positive (35% IgM anti-PS-positive) and that these prevalence figures were significantly higher than those seen in patients with SLE and no APS (IgG anti-PS in 22%, IgM anti-PS in 14%).