This article is about human blood types (or blood groups). For animal blood types, see blood type (non-human). A blood type (also called a blood group) is a classification of blood based on the presence or absence of inheritedantigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins or glycolipids, depending on the blood group system, and some of these antigens are also present on the surface of other types of cells of various tissues. Several of these red blood cell surface antigens, that stem from one allele (or very closely linked genes), collectively form a blood group system.
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