Hot spots in the red cell membrane: molecular aspects of some red cell antigens.

After decades of studying the human blood groups by serological and, more recently, biochemical techniques, analysis of blood group genes at the molecular level has confirmed that a variety of different genetical events have given rise to the vast complexity of blood group systems. In order to illustrate this 4 blood group systems have been selected: ABO and H, involving carbohydrate determinants, and MNS and Rh, involving predominantly protein antigens. The molecular basis of the A1, A2, B, and O groups, and of the rare H-deficiency phenotypes will be described. The Sta antigen of the MNS system will be discussed in order to illustrate the variety of different genetic mechanisms that can give rise to a single rare antigen. Finally, recent work on the molecular basis of the polymorphic Rh antigens, D, C, c, E, and e, and on some rare Rh phenotypes, Rhnull, D--, and r's, will be explained briefly in order to emphasize the complexity of blood group genetics.