title: Screening the expression of ABCB6 in erythrocytes reveals an unexpectedly high frequency of Lan mutations in healthy individuals.
abstract: Lan is a high-incidence blood group antigen expressed in more than 99.9% of the population. Identification of the human ABC transporter ABCB6 as the molecular basis of Lan has opened the way for studies assessing the relation of ABCB6 function and expression to health and disease. To date, 34 ABCB6 sequence variants have been described in association with reduced ABCB6 expression based on the genotyping of stored blood showing weak or no reactivity with anti-Lan antibodies. In the present study we examined the red blood cell (RBC) surface expression of ABCB6 by quantitative flow cytometry in a cohort of 47 healthy individuals. Sequencing of the entire coding region of the ABCB6 gene in low RBC ABCB6 expressors identified a new allele (IVS9+1G>A, affecting a putative splice site at the boundary of exon 9) and two nonsynonymous SNPs listed in the SNP database (R192Q (rs150221689) and G588 S (rs145526996)). The R192Q mutation showed co-segregation with reduced RBC ABCB6 expression in a family, and we found the G588 S mutation in a compound heterozygous individual with undetectable ABCB6 expression, suggesting that both mutations result in weak or no expression of ABCB6 on RBCs. Analysis of the intracellular expression pattern in HeLa cells by confocal microscopy indicated that these mutations do not compromise overall expression or the endolysosomal localization of ABCB6. Genotyping of two large cohorts, containing 235 and 1039 unrelated volunteers, confirmed the high allele frequency of Lan-mutations. Our results suggest that genetic variants linked to lower or absent cell surface expression of ABCB6/Langereis may be more common than previously thought.
authors.affiliation: Hungarian National Blood Transfusion Service, Budapest, Hungary.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Koszarska
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Nora
authors.initials: N
authors.lastname: Kucsma
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Kiss
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Varady
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Melinda
authors.initials: M
authors.lastname: Gera
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Geza
authors.initials: G
authors.lastname: Antalffy
authors.affiliation: Hungarian National Blood Transfusion Service, Budapest, Hungary.
authors.forename: Hajnalka
authors.initials: H
authors.lastname: Andrikovics
authors.affiliation: Hungarian National Blood Transfusion Service, Budapest, Hungary.
authors.forename: Attila
authors.initials: A
authors.lastname: Tordai
authors.affiliation: Department of Molecular Biophysics, University of Lodz, Lodz, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Studzian
authors.affiliation: Biobank Lab, Department of Molecular Biophysics, University of Lodz, Lodz, Poland.
authors.forename: Dominik
authors.initials: D
authors.lastname: Strapagiel
authors.affiliation: Department of Molecular Biophysics, University of Lodz, Lodz, Poland.
authors.forename: Lukasz
authors.initials: L
authors.lastname: Pulaski
authors.affiliation: Japanese Red Cross Kinki Block Blood Center, Osaka, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Tani
authors.affiliation: Hungarian National Blood Transfusion Service, Budapest, Hungary; Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary; Molecular Biophysics Research Group of the Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary.
authors.forename: Balazs
authors.initials: B
authors.lastname: Sarkadi
authors.affiliation: Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Gergely
authors.initials: G
authors.lastname: Szakacs
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000328:Adult; D000368:Aged; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D006262:Health; D006579:Heterozygote; D006801:Humans; D007519:Isoantigens / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D059645:Mutation Rate; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D013347:Subcellular Fractions
chemical_list: C107991:ABCB6 protein, human; D018528:ATP-Binding Cassette Transporters; D007519:Isoantigens; C083301:LAN antigen