title: Serological characteristic and molecular basis of A2 subgroup in the Chinese population.
abstract: BACKGROUND
  A2 phenotype is a common subgroup of blood group A, but the serological characteristic and genetics basis of A2 phenotype currently was rare reported in the Chinese Han population. Here, a large scale study of the serology and genetics of A2 and A2B phenotypes was performed.
  
  
  METHODS
  11263 Chinese individuals with group A and AB phenotypes were determined for A2 antigen with the standard serological method. The full coding region of the ABO gene was sequenced in the individuals with A2 and A2B phenotypes. Some samples including each ABO genotypes were chosen for determining the activity of glycosyltransferase A (GTA) in plasma.
  
  
  RESULTS
  134 individuals were assigned as A2 and A2B phenotypes in 11263 individuals. There was imbalance in A2 and A2B phenotypes and the proportion of A2B among AB samples was significantly higher than that of A2 in group A samples. All samples of the A2 and A2B phenotypes were classified into A2-related allele group, A1-related allele group and the other group based on kind of the ABO genotype. Four novel A2-related alleles (A217, A218, A219, A220) were identified. The individuals with same genotype showed different agglutination strength with anti-A1 and anti-H on their RBCs. The plasma from individuals with A2-related allele had almost no GTA activity, while plasma from individuals with A1-related allele had some GTA activity.
  
  
  CONCLUSIONS
  A2 and A2B phenotypes could derive from different genotypes and the serological characteristic may be heterogeneity in the Chinese Han population.
authors.affiliation: Blood Center of Zhejiang Province, Hangzhou, Zhejiang, People's Republic of China.
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Ying
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Hong
authors.forename: Xianguo
authors.initials: X
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Lan
authors.forename: Kairong
authors.initials: K
authors.lastname: Ma
authors.forename: Hong
authors.initials: H
authors.lastname: Zhu
authors.forename: Faming
authors.initials: F
authors.lastname: Zhu
authors.forename: Hangjun
authors.initials: H
authors.lastname: Lv
authors.forename: Lixing
authors.initials: L
authors.lastname: Yan
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics* / Q000276:immunology; D000483:Alleles; D044466:Asian People; D001483:Base Sequence; D001782:Blood Donors; D005838:Genotype; D006801:Humans; D010641:Phenotype
chemical_list: D000017:ABO Blood-Group System