PRB2 and autoimmune polyendocrinopathy: Most importantly, presence of either anti-β2GPI or the rarely evaluated anti-PS antibodies in 13% and 41%, respectively, of all women experiencing at least two implantation failures in IVF-ET and in virtually none of control subjects suggests that these may be very accurate biomarkers (more accurate than the more frequently measured anti-PL antibodies) and urges further evaluation of their potential clinical use in infertility, as well as in APS in general.