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Studies on the genetic basis of Pk, P and P1 blood group antigen expression

Hellberg, Åsa LU (2007)
Abstract
The clinically important carbohydrate P/GLOB blood group systems and collection give rise to both common (P1, P2) and rare (p, P1k, P2k) blood group phenotypes. The associated antibodies are implicated in severe transfusion reactions and recurrent spontaneous abortions. The aim of this study was to explore the molecular genetic basis of Pk, P and P1 antigen expression.



Sequence analysis of the A4GALT and B3GALNT1 genes proposed to synthesize the related Pk (Gb3) and P (Gb4) antigens, respectively, were performed in p and Pk individuals (n=99) of different geographic/ethnic origin. A total of 24 novel mutations were identified, emphasizing the genetic heterogeneity at the glycosyltransferase loci underlying these blood... (More)
The clinically important carbohydrate P/GLOB blood group systems and collection give rise to both common (P1, P2) and rare (p, P1k, P2k) blood group phenotypes. The associated antibodies are implicated in severe transfusion reactions and recurrent spontaneous abortions. The aim of this study was to explore the molecular genetic basis of Pk, P and P1 antigen expression.



Sequence analysis of the A4GALT and B3GALNT1 genes proposed to synthesize the related Pk (Gb3) and P (Gb4) antigens, respectively, were performed in p and Pk individuals (n=99) of different geographic/ethnic origin. A total of 24 novel mutations were identified, emphasizing the genetic heterogeneity at the glycosyltransferase loci underlying these blood groups. As a result of this study, the P antigen was assigned its own blood group system, GLOB (028), by ISBT.



Expression studies in the Pk-negative Namalwa cells transfected with mutated A4GALT-constructs showed Pk expression levels comparable to negative controls. RBCs with p phenotype showed no Pk and P activity while both P and Pk expression on RBCs varied considerably between individuals with common phenotypes.



Sixteen polymorphic sites were detected while investigating if polymorphisms in the regulatory region of the A4GALT gene might be the basis for the P1/P2 phenotypes. No clear-cut correlation was found and two previously proposed P2-specific mutations were detected in homozygous form both in P1 and P2 donors indicating that these mutations are not the sole cause of the P1/P2 status. However, the correlation between the A4GALT locus and P2 status seems to be rather strong (Less)
Abstract (Swedish)
Popular Abstract in Swedish

Blodgruppsantigen finns på den röda blodkroppens cellyta och även på många andra celltyper.



I denna avhandling har jag studerat gener och dess varianter (polymorfismer) som är ansvariga för uttrycket av tre blodgruppsantigener av kolhydratnatur, nämligen Pk, P och P1. Dessa utgör P- och GLOB-blodgruppssystemen och GLOB-kollektionen. Fem olika fenotyper förekommer då antigenen Pk, P eller P1 saknas i olika kombinationer: P1, P2, p, P1k och P2k. De tre sistnämnda är mycket ovanliga, enstaka per miljon människor, och gör att endast blod med samma fenotyp kan transfunderas. Hos kvinnor med fenotyperna p, P1k och P2k är förekomsten av återkommande missfall högre än hos andra... (More)
Popular Abstract in Swedish

Blodgruppsantigen finns på den röda blodkroppens cellyta och även på många andra celltyper.



I denna avhandling har jag studerat gener och dess varianter (polymorfismer) som är ansvariga för uttrycket av tre blodgruppsantigener av kolhydratnatur, nämligen Pk, P och P1. Dessa utgör P- och GLOB-blodgruppssystemen och GLOB-kollektionen. Fem olika fenotyper förekommer då antigenen Pk, P eller P1 saknas i olika kombinationer: P1, P2, p, P1k och P2k. De tre sistnämnda är mycket ovanliga, enstaka per miljon människor, och gör att endast blod med samma fenotyp kan transfunderas. Hos kvinnor med fenotyperna p, P1k och P2k är förekomsten av återkommande missfall högre än hos andra kvinnor. P/GLOB-antigenen fungerar även som receptorer (mottagare) för vissa virus, bakterier och deras toxiner.



Generna A4GALT och B3GALNT1 som syntetiserar Pk (Gb3) respektive P (Gb4) antigen, sekvenerades i p och Pk individer (n=99) med olika geografiskt och etniskt ursprung. Totalt hittades 24 nya mutationer. P-antigenet tillhörde tidigare GLOB-kollektionen eftersom den genetiska bakgrunden varit oklar men baserat på våra resultat fick P-antigenet ett eget blodgruppssystem, GLOB (ISBT nummer 028). En av de nyupptäckta mutationerna användes i expressionsstudier i en Pk-negativ cellinje. Cellerna transfekterade med ett muterat A4GALT-konstrukt visade samma uttryck som de negativa kontrollerna. Både Pk- och P-uttrycket mättes på röda blodkroppar från p-individer och svenska blodgivare med normala/vanliga blodgruppsfenotyper. Blodkroppar med p-fenotyp visade inget uttryck medan variationen hos vanliga individer var förvånansvärt stort.



Genen för P1 har ännu inte hittats men en japansk forskargrupp föreslog att två polymorfismer i A4GALT-genens reglerande del (5?-uppströmsregion) skulle vara kopplad till förekomsten av P1-antigenet respektive avsaknad av detsamma. Sjuttioåtta individer undersöktes och alla P2-prover var homozygota för de s.k P2-mutationerna. Dock hittades även P1-prover som var homozygota för samma mutationer. Därmed blir slutsatsen att de föreslagna P2-polymorfismerna inte enbart kan vara de som styr P1/P2-blodgruppsuttrycket



Sammantaget har den bakomliggande orsaken till ett flertal Pk/P/P1-relaterade blodgrupper utretts. Detta gör att vi idag vet lite mer om genetiken som styr dessa kliniskt viktiga skillnader mellan olika individer. Kunskapen kan bl.a. utnyttjas för vidare utveckling av DNA-baserad blodgruppsbestämning. Det vore också intressant att fortsätta studera samspelet mellan Pk/P/P1-antigenen och olika virus eller bakterier. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Spitalnik, Steven, Department of Pathology, Lab Med, Columbia University, NY;USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Immunologi, serology, serologi, transplantation, Immunology, SNP, phenotype, erythrocyte, blood group, glycosyltransferase
pages
125 pages
publisher
Department of Laboratory Medicine, Lund University
defense location
Segerfalksalen, Wallenberg Neurocentrum, BMC, Sölvegatan 17, Lund
defense date
2007-03-16 13:00:00
ISBN
978-91-85559-15-2
language
English
LU publication?
yes
additional info
Åsa Hellberg, Joyce Poole and Martin L Olsson. 2002. Molecular Basis of the Globoside-Deficient Pk Blood Group Phenotype. Identification of Four Inactivating Mutations in the UDP-N-acetyl-galactosamine:globotriasyl- ceramide 3-?-N-acetylgalactosaminyltransferase Gene. Journal of Biological Chemistry, vol 277 pp 29455-9.
Åsa Hellberg, Rudi Steffensen, Vered Yahalom, Birgitta Nilsson Sojka, Hans Erik Heier, Levene Cyril, Joyce Poole and Martin L Olsson. 2003. Additional molecular bases of the clinically important p blood group phenotype. Transfusion, vol 43 pp 899-907.
Åsa Hellberg, Arturo Ringressi, Vered Yahalom, Jan Säfwenberg, Marion E Reid and Martin L Olsson. 2004. Genetic heterogeneity at the glycosyltransferase loci underlying the GLOB blood group system and collection British Journal of haemtology, vol 125 pp 528-536. Blackwell
Åsa Hellberg, Alan M Chester and Martin L Olsson. 2005. Two previously proposed P1/P2-differentiating and nine novel polymorphisms at the A4GALT (Pk) locus do not correlate with the presence of the P1 blood group antigen BMC Genetics, vol 6 pp 11 pages. BioMed Central
Åsa Hellberg, Anne-Christine Schmidt-Melbye, Marion E Reid and Martin L Olsson. . Expression of a novel missense mutation found in the A4GALT gene of Amish individuals with the p phenotype (submitted)
id
8be57660-0c26-41ce-aecb-2469ee041983 (old id 548167)
date added to LUP
2016-04-01 16:00:13
date last changed
2018-11-21 20:38:01
@phdthesis{8be57660-0c26-41ce-aecb-2469ee041983,
  abstract     = {{The clinically important carbohydrate P/GLOB blood group systems and collection give rise to both common (P1, P2) and rare (p, P1k, P2k) blood group phenotypes. The associated antibodies are implicated in severe transfusion reactions and recurrent spontaneous abortions. The aim of this study was to explore the molecular genetic basis of Pk, P and P1 antigen expression.<br/><br>
<br/><br>
Sequence analysis of the A4GALT and B3GALNT1 genes proposed to synthesize the related Pk (Gb3) and P (Gb4) antigens, respectively, were performed in p and Pk individuals (n=99) of different geographic/ethnic origin. A total of 24 novel mutations were identified, emphasizing the genetic heterogeneity at the glycosyltransferase loci underlying these blood groups. As a result of this study, the P antigen was assigned its own blood group system, GLOB (028), by ISBT.<br/><br>
<br/><br>
Expression studies in the Pk-negative Namalwa cells transfected with mutated A4GALT-constructs showed Pk expression levels comparable to negative controls. RBCs with p phenotype showed no Pk and P activity while both P and Pk expression on RBCs varied considerably between individuals with common phenotypes.<br/><br>
<br/><br>
Sixteen polymorphic sites were detected while investigating if polymorphisms in the regulatory region of the A4GALT gene might be the basis for the P1/P2 phenotypes. No clear-cut correlation was found and two previously proposed P2-specific mutations were detected in homozygous form both in P1 and P2 donors indicating that these mutations are not the sole cause of the P1/P2 status. However, the correlation between the A4GALT locus and P2 status seems to be rather strong}},
  author       = {{Hellberg, Åsa}},
  isbn         = {{978-91-85559-15-2}},
  keywords     = {{Immunologi; serology; serologi; transplantation; Immunology; SNP; phenotype; erythrocyte; blood group; glycosyltransferase}},
  language     = {{eng}},
  publisher    = {{Department of Laboratory Medicine, Lund University}},
  school       = {{Lund University}},
  title        = {{Studies on the genetic basis of Pk, P and P1 blood group antigen expression}},
  url          = {{https://lup.lub.lu.se/search/files/4540285/548168.pdf}},
  year         = {{2007}},
}