title: [Sequence analysis of O04 allele expression of A antigen].
abstract: OBJECTIVE
  To study the molecular basis of O04 allele expression of weak A antigen at the ABO locus.
  
  
  METHODS
  Serological assays were performed to characterize the erythrocyte phenotype of a proband. Mutations of the ABO gene were screened with polymerase chain reaction (PCR), reverse-transcription PCR (RT-PCR) and DNA sequencing.
  
  
  RESULTS
  The proband was identified as weak AB phenotype by serological assays. A B101 allele and an O04 allele were identified by gene sequencing, gene cloning and RT-PCR.
  
  
  CONCLUSIONS
  A B101 allele and an O04 allele were confirmed by the sequencing based typing in a suspicious ABO blood group. The O04 allele is characterized by expression of weak A antigen.
authors.affiliation: Liaoning Blood Center, Shenyang, Liaoning 110044, P. R. China. ljp_63@163.com.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Jianping
authors.initials: J
authors.lastname: Li
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D000328:Adult; D001483:Base Sequence; D002681:China; D005091:Exons; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D055815:Young Adult
chemical_list: D000017:ABO Blood-Group System