SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "L773:1537 2995 ;pers:(Chester Alan)"

Sökning: L773:1537 2995 > Chester Alan

  • Resultat 1-5 av 5
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Hosseini Maaf, Bahram, et al. (författare)
  • 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
  • Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 47:11, s. 2110-2125
  • 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.
  •  
2.
  •  
3.
  • Hosseini Maaf, Bahram, et al. (författare)
  • Structural basis for red cell phenotypic changes in newly identified, naturally occurring subgroup mutants of the human blood group B glycosyltransferase.
  • 2007
  • Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 47:5, s. 864-875
  • 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.
  •  
4.
  • Olsson, Martin L, et al. (författare)
  • Polymorphisms at the ABO locus in subgroup A individuals
  • 1996
  • Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 36:4, s. 309-313
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The common ABO allele sequences are known, but little or no genetic information is available on the rare but important A subgroups. STUDY DESIGN AND METHODS: Blood group ABO polymorphism was analyzed in genomic DNA from 45 rare subgroup A individuals by sequence-specific primer polymerase chain reaction and amplified fragment length polymorphism investigating exons VI and VII in the ABO genes. These methods are used to detect specific mutations only, and not all changes that might be present can be detected. ABO genotypes discriminating six alleles (A1, A2, B, O1, O1var, and O2) were determined. RESULTS: The C-->T substitution at nucleotide position 467 (C467T) is not restricted to A2 and cis-AB individuals, but was found also in some A subgroups. Detection of the functionally more relevant C1060-single-point deletion in A2 was accomplished by a novel sequence-specific primer polymerase chain reaction approach. A 100-percent correlation between the C467T and the C1060-mutations was found. Fifteen of 17 samples showing the T646A mutation (described earlier in one case of Ax) showed a positive correlation with the C771T mutation in a frequently occurring O1var allele. The two exceptions were defined serologically as Ax. CONCLUSION: Indications have been found of an evolutionary relationship between A1 alleles and Ael and A3 subgroups as well as between A2 alleles and Aend and Aweak subgroups. Genetic heterogeneity within the Ax and Aint subgroups was also seen.
  •  
5.
  • Thuresson, Britt, et al. (författare)
  • ABO transcript levels in peripheral blood and erythropoietic culture show different allele-related patterns independent of the CBF/NF-Y enhancer motif and multiple novel allele-specific variations in the 5'- and 3'-noncoding regions.
  • 2008
  • Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 48:3, s. 493-504
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Mechanisms regulating the ABO gene are unclear, especially in the hematopoietic compartment. The number of 43-bp repeats in the CBF/NF-Y-binding enhancer region is considered to have a major influence on transcription. STUDY DESIGN AND METHODS: Transcript levels in peripheral blood and in erythropoietic culture of CD34+ cells from marrow donors were measured with TaqMan assays. The 5'-regulatory region and 3'-downstream sequences were investigated to determine if allelic variations occur. RESULTS: Surprisingly, transcripts from A(1) and A(2) alleles could not be detected in peripheral blood, although transcripts from B/O(1)/O(1v)/O(2) alleles were readily observed. Sequencing of approximately 4 kb upstream and 1.8 kb downstream of the coding region showed multiple novel allele-specific and allele-related motifs. No correlation between these sequence variations and transcript levels was found, however. Contradictory to the results with peripheral blood, in erythropoietic culture of CD34+ cells from healthy marrow donors transcripts from A(1) and A(2) alleles were found at higher levels than transcripts from B/O(1)/O(1v) alleles. CONCLUSION: These data do not support previous suggestions that nonsense-mutated O(1)/O(1v) transcripts are eliminated first. Furthermore, our results contradict the notion that the number of repeats in the upstream CBF/NF-Y-binding enhancer region, which contains four 43-bp repeats in A(2)/B/O(1)/O(1v) but only one 43-bp unit in A(1)/O(2) alleles, determines the transcription rate. The reason for the remarkable discrepancy between blood and marrow remains to be elucidated.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-5 av 5

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy