title: Molecular genetic analysis for Ax phenotype of the ABO blood group system in Chinese.
abstract: OBJECTIVE
  To elucidate the molecular genetic background of the Ax phenotype in the Chinese population.
  
  
  METHODS
  The ABO genes of eight Ax phenotype samples, four Ax and four AxB, were amplified by polymerase chain reaction (PCR) and were cloned, along with those of 10 random A(1) Chinese subjects. We analysed the ABO gene transcript structure and the sequences of two exons and one intron at the ABO locus.
  
  
  RESULTS
  Among the four Ax phenotype samples, we identified one Ax02, two Ax03 and one novel Ax allele with the 543G > T mutation in the A102 background. Two of five family members also carry the allele. Of the four AxB phenotypes, one was designated as cis-AB-1/B101; the other three were shown to carry one B allele and one O with the nt261G deletion. The B alleles of the latter three were identical to B101 except for single point mutation at nt700C > G, nt640A > G and nt641T > C, respectively. The novel B101-like alleles were first associated with A(weak)B phenotypes.
  
  
  CONCLUSIONS
  Two ABO*B(A) alleles and an Ax allele clearly differ from all previously reported ABO alleles, suggesting that the molecular genetic background of Ax is heterogeneous in the Chinese population.
authors.affiliation: Shenzhen Institute of Transfusion Medicine, Shenzhen, Guangdong, China. zhihui_deng@yahoo.com.cn
authors.forename: Z H
authors.initials: ZH
authors.lastname: Deng
authors.forename: Q
authors.initials: Q
authors.lastname: Yu
authors.forename: G G
authors.initials: GG
authors.lastname: Wu
authors.forename: Y L
authors.initials: YL
authors.lastname: Lian
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Su
authors.forename: D C
authors.initials: DC
authors.lastname: Li
authors.forename: D M
authors.initials: DM
authors.lastname: Wang
authors.forename: S Y
authors.initials: SY
authors.lastname: Zhang
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D000483:Alleles; D044466:Asian People; D002681:China; D004252:DNA Mutational Analysis / Q000379:methods; D005091:Exons / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D010641:Phenotype; D017354:Point Mutation; D040641:Quantitative Trait Loci / Q000235:genetics*
chemical_list: D000017:ABO Blood-Group System