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- Sjöberg Wester, Elisabet, et al.
(författare)
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Genetic basis of the K phenotype in the Swedish population.
- 2005
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Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 45:4, s. 545-549
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined BACKGROUND: The absence of all Kell blood group antigens (K0 phenotype) is very rare. K0 persons, however, can produce clinically significant anti-Ku (K5) after transfusion and/or pregnancy and require K0 blood for transfusion. Ten alleles giving rise to the K0 phenotype have been reported: different populations were studied although none from Scandinavia. STUDY DESIGN AND METHODS: Three K0 samples were identified by blood banks in Sweden (Uppsala,Umeå, and Linköping) during a 20-year period. Kell antigen typing was performed with standard serologic techniques by the respective blood banks and K 0 status was confirmed by the International Blood GroupReference Laboratory in Bristol, England. Polymerase chain reaction and DNA sequencing of the KEL coding region (exons 1-19) was performed on genomic DNA. RESULTS:The Uppsala K0 was homozygous for a 1540C>T substitution in exon 13, leading to an immediate stop codon. The Umeå K0 was homozygous for 1023delG in exon 8 that results in a frameshift and a premature stop codon in exon 9. In the Linköping K0, a previously reported mutation g>a at +1 of intron 3 was found. CONCLUSION: Two novel and one previously reported null alleles at the KEL locus are described. The identified nonsense mutations abolish expression of the Kell glycoprotein and are thus responsible for the K0 phenotype in these Swedish families.
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| 6. |
- Hellberg, Åsa, et al.
(författare)
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Expression of a novel missense mutation found in the A4GALT gene of Amish individuals with the p phenotype.
- 2008
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Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 48:3, s. 479-487
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The rare p phenotype is found at a higher frequency in Amish people than in other populations. Different mutations in the 4-alpha-galactosyltransferase gene (A4GALT), responsible for synthesis of P(k) (Gb(3)) antigen, have been found to cause the P(k)-deficient p phenotype. The aim of this study was to explore the molecular background of the p phenotype in people of Amish origin. STUDY DESIGN AND METHODS: Twenty blood samples with the p phenotype, 19 of them from Amish individuals and 1 Pakistani, were investigated. Amplification of genomic DNA by polymerase chain reaction (PCR) and sequencing by capillary electrophoresis were performed. Blood donors of different geographic origin were screened with PCR-allele-specific primer to investigate whether the novel mutation occurs among individuals with common phenotypes. The mutation was also cloned into an expression vector and transfected to Namalwa cells, which do not normally express P(k). P(k) expression on the transfected cells and P/P(k) on red blood cells (RBCs), both with p and with common phenotypes, were analyzed by flow cytometry. RESULTS: All 20 samples were homozygous for 299C>T changing serine to leucine in a region that is highly conserved in homologous genes across species borders. The mutation was not found in any of the 500 alleles of blood donors investigated. P(k) expression was neither observed by serology and flow cytometry on p RBCs from Amish individuals nor following transfection of cells with constructs containing the novel missense mutation. CONCLUSION: A novel A4GALT missense mutation causes the p phenotype in Amish individuals.
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| 7. |
- Hosseini Maaf, Bahram, et al.
(författare)
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An extensive polymerase chain reaction-allele-specific polymorphism strategy for clinical ABO blood group genotyping that avoids potential errors caused by null, subgroup, and hybrid alleles
- 2007
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Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 47:11, s. 2110-2125
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Tidskriftsartikel (refereegranskat)abstract
- Background: ABO genotyping is complicated by the remarkable diversity at the ABO locus. Recombination or gene conversion between common alleles may lead to hybrids resulting in unexpected ABO phenotypes. Furthermore, numerous mutations associated with weak subgroups and nondeletional null alleles should be considered. All known ABO genotyping methods, however, risk incorrect phenotype predictions if any such alleles are present. Study Design and Methods: An extensive set of allele-specific primers was designed to accomplish hybrid-proof multiplex polymerase chain reaction (PCR) amplification of DNA fragments for detection of ABO alleles. Results were compared with serologic findings and ABO genotypes defined by previously published PCR-restriction fragment length polymorphism/PCR-allele-specific polymorphism (ASP) methods or DNA sequencing. Results: Phenotypically well-characterized samples from blood donors with common blood groups and rare-subgroup families were analyzed. In addition to the commonly encountered alleles (A(1), A(1(467C > T)), A(2), B, O-1, O-1v, and O-2), the new method can detect hybrid alleles thanks to long-range amplification across intron 6. Four of 12 PCR-ASP procedures are used to screen for multiple infrequent subgroup and null alleles. This concept allows for a low-resolution typing format in which the presence of, for example, a weak subgroup or cis-AB/B(A) is indicated but not further defined. In an optional high-resolution step, more detailed genotype information is obtained. Conclusion: A new genotyping approach has been developed and evaluated that can correctly identify ABO alleles including nondeletional null alleles, subgroups, and hybrids resulting from recombinational crossing-over events between exons 6 and 7. This approach is clinically applicable and decreases the risk for erroneous ABO phenotype prediction compared to previously published methods.
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| 9. |
- Hosseini Maaf, Bahram, et al.
(författare)
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Structural basis for red cell phenotypic changes in newly identified, naturally occurring subgroup mutants of the human blood group B glycosyltransferase.
- 2007
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Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 47:5, s. 864-875
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Four amino-acid-changing polymorphisms differentiate the blood group A and B alleles. Multiple missense mutations are associated with weak expression of A and B antigens but the structural changes causing subgroups have not been studied. STUDY DESIGN AND METHODS: Individuals or families having serologically weak B antigen on their red cells were studied. Alleles were characterized by sequencing of exons 1 through 7 in the ABO gene. Single crystal X-ray diffraction, three-dimensional-structure molecular modeling, and enzyme kinetics showed the effects of the B allele mutations on the glycosyltransferases. RESULTS: Seven unrelated individuals with weak B phenotypes possessed seven different B alleles, five of which are new and result in substitution of highly conserved amino acids: M189V, I192T, F216I, D262N, and A268T. One of these (F216I) was due to a hybrid allele resulting from recombination between B and O-1v alleles. The two other alleles were recently described in other ethnic groups and result in V175M and L232P. The first crystal-structure determination (A268T) of a subgroup glycosyltransferase and molecular modeling (F216I, D262N, L232P) indicated conformational changes in the enzyme that could explain the diminished enzyme activity. The effect of three mutations could not be visualized since they occur in a disordered loop. CONCLUSION: The genetic background for B-w phenotypes is very heterogeneous but usually arises through seemingly random missense mutations throughout the last ABO exon. The targeted amino acid residues, however, are well conserved during evolution. Based on analysis of the resulting structural changes in the glycosyltransferase, the mutations are likely to disrupt molecular bonds of importance for enzymatic function.
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| 10. |
- Hult, Annika, et al.
(författare)
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Flow cytometry evaluation of red blood cells mimicking naturally occurring ABO subgroups after modification with variable amounts of function-spacer-lipid A and B constructs.
- 2012
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Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 52, s. 247-251
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Kodecytes bearing synthetic blood group A and B antigens are increasingly being used in transfusion laboratories as serologic mimics of red blood cell (RBC) A(weak) and B(weak) subtypes. The aim of this study was to compare the flow cytometry profile of kodecytes with native ABO subgroups. STUDY DESIGN AND METHODS: A series of A/B kodecytes, each with decreasing A or B antigen expression, were prepared from group O RBCs that were modified with dilutions of function-spacer-lipid KODE technology (FSL) constructs representing a wide serologic range. Using an established flow cytometry method designed for the detection of low levels of A/B antigens, kodecyte profiles were compared with those of native subgroup cells. RESULTS: Kodecytes with positive tube serology from 4+ to 1+ were created with 15 to 2 µg/mL FSL-A or 78 to 10 µg/mL FSL-B transformation solutions. The kodecytes created with higher concentrations of FSL constructs revealed a uniform and/or even distribution of antigens as seen by a single flow cytometry peak more narrow than the broader peaks produced with lower FSL concentrations similar to those found in native A(x) and most B(weak) subgroups. CONCLUSIONS: Although kodecytes are created artificially, they can be designed to mimic the serologic and flow cytometric profiles of native ABO subgroup RBCs.
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