title: Defining the Jr(a-) phenotype in the Japanese population.
abstract: BACKGROUND
  The Jr(a-) phenotype is rare in European and North American populations but is not so rare in Japanese and other Asian populations. Recently, two groups have established the connection between the Jr(a-) phenotype and the ATP-binding cassette, member G2 (ABCG2) gene and concluded that ABCG2-null alleles encode the Jr(a-) phenotype. In Japanese Red Cross Blood Centers, the Jr(a-) phenotype is found with a prevalence of 0.05% among blood donors, and we applied DNA-based genotyping to investigate the molecular basis of the Jr(a-) phenotype in Japan, in addition to serologic typing.
  
  
  METHODS
  Purified genomic DNA extracts of Japanese donor samples [500 Jr(a+) and 85 Jr(a-) phenotypes] were amplified using specific amplification primers for the c.376C>T mutation, which is the most common mutation in the Asian JRnull allele. Polymerase chain reaction products were examined by high-resolution melt techniques and DNA sequence analyses.
  
  
  RESULTS
  Seventy-nine of 85 Jr(a-) samples were homozygous for the single-nucleotide polymorphism c.376C>T (Gln126Stop) change. In other samples, two novel null alleles were detected: c.2T>C and c.421C>A: c.1515delC.
  
  
  CONCLUSIONS
  In this study, more than 90% of the Japanese Jr(a-) phenotypes had c.376C>T (Gln126Stop) nucleotide change. In the other Jr(a-), a new mutation (c.2T>C) in the start codon encoding Thr instead of Met, c.1515delC encoding Ala505AlafsStop and heterozygous for c.337C/T and c.736C/T were detected. DNA-based genotyping is accurate and useful for Jr(a-) donor typing.
authors.affiliation: Japanese Red Cross Kinki Block Blood Center, Osaka, Japan.
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Tanaka
authors.forename: Ikuko
authors.initials: I
authors.lastname: Kamada
authors.forename: Junko
authors.initials: J
authors.lastname: Takahashi
authors.forename: Keiko
authors.initials: K
authors.lastname: Kimura
authors.forename: Harumichi
authors.initials: H
authors.lastname: Matsukura
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Tani
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000097:blood* / Q000235:genetics*; D000483:Alleles; D044466:Asian People / Q000235:genetics*; D001782:Blood Donors; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D009363:Neoplasm Proteins / Q000097:blood* / Q000235:genetics*; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D009363:Neoplasm Proteins