The Raph blood group system consists of one antigen (MER2) carried on a multipass membrane glycoprotein CD151 of the tetraspanin family. It consists of 253 amino acids and both amino and carboxyl termini are predicted to be intracellular. The glycoprotein is encoded by CD151 (or RAPH , if analysis is to predict a blood group antigen). The null phenotype is associated with renal failure.