title: A new ABCG2 null allele with a 27-kb deletion including the promoter region causing the Jr(a-) phenotype.
abstract: BACKGROUND
  The high-prevalence antigen Jr(a) is carried on the ATP-binding cassette transporter ABCG2. The ABCG2 gene consists of 16 exons and its translation start codon is located on the second exon. Although the occurrence of the Jr(a-) phenotype is rare, several ABCG2 null alleles have been reported. We report a new ABCG2 null allele having a large deletion in this study.
  
  
  METHODS
  The Jr(a) status was determined by standard serologic tests and genomic DNA was isolated from whole blood. Exons 1 to 16 and the 5'-untranslated region of the ABCG2 gene were analyzed by polymerase chain reaction and sequencing. Expression of the ABCG2 protein on red blood cells was examined by immunoblotting.
  
  
  RESULTS
  A Jr(a-) blood donor had a novel allele having a 27-kb deletion including noncoding Exon 1 and the promoter region of ABCG2, and the donor was apparently homozygous for the allele. In addition, we found three more individuals having heterozygosity for the same allele, with ABCG2*01N.01 having c.376C>T (p.Q126X), but did not find the allele having the 27-kb deletion in 3000 Jr(a+) individuals. Immunoblotting revealed that the ABCG2 protein was not found to be expressed in the individual with homozygosity for the ABCG2 27-kb deleted and in two individuals with an ABCG2 27-kb deleted/ABCG2*01N.01 genotype, which indirectly allows to conclude that the 27-kb deletion is responsible for a null ABCG2 allele.
  
  
  CONCLUSIONS
  We first identified an ABCG2 null allele (provisional ISBT allele number ABCG2*01N.23) having a large deletion including the promoter region.
authors.affiliation: Japanese Red Cross Central Blood Institute, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ogasawara
authors.affiliation: Japanese Red Cross Kanto-Koshinetsu Block Blood Center, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Osabe
authors.affiliation: Japanese Red Cross Kanto-Koshinetsu Block Blood Center, Tokyo, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Japanese Red Cross Kanto-Koshinetsu Block Blood Center, Tokyo, Japan.
authors.forename: Hatsue
authors.initials: H
authors.lastname: Tsuneyama
authors.affiliation: Japanese Red Cross Central Blood Institute, Tokyo, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Isa
authors.affiliation: Japanese Red Cross Kanto-Koshinetsu Block Saitama Blood Center, Saitama, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Kawai
authors.affiliation: Japanese Red Cross Kanto-Koshinetsu Block Saitama Blood Center, Saitama, Japan.
authors.forename: Kumi
authors.initials: K
authors.lastname: Obara
authors.affiliation: Japanese Red Cross Tohoku Block Blood Center, Miyagi, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Ogiyama
authors.affiliation: Japanese Red Cross Tohoku Block Blood Center, Miyagi, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Ito
authors.affiliation: Japanese Red Cross Kanto-Koshinetsu Block Blood Center, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchikawa
authors.affiliation: Japanese Red Cross Central Blood Institute, Tokyo, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Satake
authors.affiliation: Japanese Red Cross Central Blood Institute, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tadokoro
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D001483:Base Sequence; D001782:Blood Donors; D001789:Blood Group Antigens / Q000235:genetics* / Q000276:immunology; D004912:Erythrocytes / Q000276:immunology; D017353:Gene Deletion; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009363:Neoplasm Proteins / Q000235:genetics*; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics*
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D001789:Blood Group Antigens; D009363:Neoplasm Proteins