The Emm red blood cell antigen is assigned number 901008 in the International Society of Blood Transfusion (ISBY) 901 series of high incidence antigens. Emm has been designated the 42nd blood group system. Rare individuals have an Emm- phenotype due to homozygous loss-of-function mutations in the PIGG gene. These individuals often have naturally occurring anti-Emm antibodies that are identified during routine blood type and crossing. These antibodies have the potential to cause acute hemolytic transfusion reactions (summary by Lane et al., 2021). [from
OMIM]