Study of a family with a variant M antigen

Anti-M antibody was found in the serum of a 64-year-old woman during a routine pre-operative screen. Her red cell type was MN but the antibody was shown not to be an autoantibody. Blood tests were run on other members of her family, and it was found that her sister's red cells, also type MN, were not agglutinated by the patient's IgM antibody. Chemical studies are reported on the red cell surface glycoproteins of the patient and 2 family members. This red cell variant is compared with previous reports of Ma and is believed to be a further example of this blood type.