title: The ABO blood group gene: a locus of considerable genetic diversity.
abstract: The blood group ABO gene shows considerable polymorphism in most of the 7 exons. Introns examined so far have also shown blood group-related polymorphisms, as has an upstream enhancer region. Several polymorphisms affect the specificity of the gene product (glycosyltransferase) and explain the occurrence of blood group A and B. Various lethal mutations result in blood group O. Other mutations are presumed to alter the activity rather than the specificity of the enzyme and result in weaker A and B blood group phenotypes. In total, 27 A alleles, 15 B alleles, 26 O alleles, and 4 AB hybrid alleles are described and surely more will surface in the near future. Variation in geographic/ethnic distribution of allele frequencies is discussed, along with the confusing nomenclatures currently in use.
authors.affiliation: Department of Transfusion Medicine, Institute of Laboratory Medicine, Lund University, and the Blood Centre, University Hospital, Lund, Sweden.
authors.forename: M A
authors.initials: MA
authors.lastname: Chester
authors.forename: M L
authors.initials: ML
authors.lastname: Olsson
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D000483:Alleles; D014644:Genetic Variation; D016695:Glycosyltransferases; D006801:Humans; D009154:Mutation; D044469:Racial Groups / Q000235:genetics
chemical_list: D000017:ABO Blood-Group System; D016695:Glycosyltransferases