title: [Molecular genetic analysis of an Ax13B phenotype of ABO subtype].
abstract: OBJECTIVE
  To explore the molecular basis for a rare Ax13B phenotype of the ABO subtype.
  
  
  METHODS
  Serological assays were carried out to characterize the erythrocyte phenotype of the discrepant sample. Exons 6 and 7 of the ABO gene were amplified with polymerase chain reaction and subjected to direct sequencing. The amplicons were also cloned to separate the two alleles.
  
  
  RESULTS
  Both A and B antigens were detected on the red blood cells of the proband, and anti-A antibody was detected in the serum. The serological phenotype of the sample was identified as AxB. DNA sequencing showed heterozygous status for 297AG, 526CG, 657CT, 703AG, 796AC, 803GC, 930GA and 940AG in exons 6 and 7. After cloning and sequencing, two alleles Ax13 and B101 were obtained. The sequence of Ax13 showed a nucleotide change (A to G) at position 940.
  
  
  CONCLUSIONS
  The 940A>G mutation of the α-1,3-N-acetylgalactosaminyltransferase gene has resulted in the reduced expression of 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*; D000483:Alleles; D001483:Base Sequence; D001788:Blood Grouping and Crossmatching / Q000379:methods*; D005091:Exons / Q000235:genetics; D005838:Genotype; D060005:Genotyping Techniques / Q000379:methods*; D006579:Heterozygote; D006801:Humans; D008297:Male; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics; D010641:Phenotype; D017354:Point Mutation; D017422:Sequence Analysis, DNA / Q000379:methods*
chemical_list: D000017:ABO Blood-Group System; D017350:N-Acetylgalactosaminyltransferases