The FcRn (FCGRT/B2M) blocker (Fc-Tag) is a purified human protein corresponding to the Fc region of an antibody which has been engineered to bind to human neonatal Fc Receptor for IgG (FcRn; FCGRT/B2M) with high affinity. This protein has been tested for specific binding to human FcRn (BPS Bioscience #71283) and it blocks the binding of FcRn to IgG. The FcRn blocker is equivalent to Efgartigimod alfa-fcab, sold under the brａnd name Vyvgart® by Argenx.