Hypercatabolic hypoproteinemia is a disorder of endogenous catabolism of albumin and immunoglobulin. FcRn is a heterodimeric receptor composed of a nonclassical MHC class I alpha-chain and beta-2-microglobulin (B2M) that binds two ligands, IgG and albumin. It has been suggested that a mutation in B2M gene causes this disease.
