| 1. |
- Araujo, F, et al.
(författare)
-
Weak D type 2 is the most prevalent weak D type in Portugal
- 2006
-
Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 16:1, s. 63-67
-
Tidskriftsartikel (refereegranskat)abstract
- The weak D phenotype is the most common D variant, with a frequency of 0.2-1% in Caucasian individuals. There are several weak D types, with different frequencies in European countries, which may pose serologic problems and have the potential for alloimmunization. Samples from Portuguese individuals were tested for RhD by two or three distinct monoclonal and oligoclonal antisera, in direct agglutination tests. When discrepant results were observed, samples were tested with panels of monoclonal anti-D by LISS-indirect antigobulin test. Cases that reacted weakly with IgM but positive with IgG anti-D were analysed by PCR-sequence-specific primers and real-time PCR. Ninety-nine samples were referred after being characterized as weak D. This genotype was recognized, with a preponderance of weak D type 2 (63.6%) over type 1 (16.2%) and 3 (14.1%). The high incidence of weak D type 2 in our population is in marked contrast to studies performed in other European populations and might be due to our sample selection criteria or ethnic variation. There are advantages in genotyping serologically depressed D samples to avoid the waste of D-negative RBC units and the use of immunoglobulin in pregnant women, who have no risk of alloimmunization.
|
|
| 2. |
- Estalote, AC, et al.
(författare)
-
A novel blood group B subgroup: serological and genetic studies
- 2004
-
Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 14:2, s. 173-180
-
Tidskriftsartikel (refereegranskat)abstract
- A discrepancy in the ABO blood groups between a newborn child and her parents was identified. Serological and DNA investigative techniques were performed. A weak variant of B (B-w) was detected on the erythrocytes of the child, her grandmother and great-uncle. Adsorption-elution studies showed that their erythrocytes adsorb and yield anti-B on elution. The B-w antigenic strength of the A(1)B(w) cells of her mother and maternal aunt was reduced when compared to that of the A(2)B(w) from another family member. Only one of 15 different anti-B sera agglutinated the A(1)B(w) erythrocytes. Agglutinin anti-B that reacted strongly with normal B erythrocytes and did not agglutinate the B-w cells, was found in the sera of the A(1)B(w) individuals. The B-w serum glycosyltransferase could not convert O cells into B cells and no B substance was found in saliva. All family members with the B-w/AB(w) phenotypes were heterozygous for a B allele and DNA sequencing revealed a novel missense mutation in exon 7 of the B allele (556A > G), resulting in M186V. This substitution changes a highly conserved region of the enzyme, proposed to be a disordered loop near the enzyme cleft, and is expected to diminish the enzyme's activity, leading to this B-w phenotype.
|
|
| 3. |
- Irshaid, N M, et al.
(författare)
-
Allele-related variation in minisatellite repeats involved in the transcription of the blood group ABO gene
- 1999
-
Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 9:3, s. 219-226
-
Tidskriftsartikel (refereegranskat)abstract
- Since the cloning in 1990 of cDNA corresponding to mRNA transcribed at the blood group ABO locus, polymorphisms at the ABO locus and phenotype-genotype correlation have been analysed by several investigators. An enhancer-active minisatellite motif reported to contain four 43-bp repeats has been analysed by PCR in blood samples from 160 random Swedish blood donors. Different sizes of the DNA fragments obtained led to further analysis by direct sequencing. Fragments with either one or four 43-bp repeats were identified. A nucleotide substitution (G-->A) at nt. 41 of 43 was found in all alleles with only one repeat. Correlation with the ABO genotypes of the samples, as determined by a panel of ABO genotyping techniques, revealed an allele-related variable number of tandem repeats (VNTR). The A1 and the infrequent O2 allele had only one repeat whilst A2, B, O1 and O1v had four repeats and thus generated longer (by 129 bp) fragments. A further 74 samples obtained from various geographical areas/ethnic groups indicated a widespread correlation with few exceptions. In conclusion, a novel ABO polymorphism located in the 5'-nontranslated region involved in transcriptional regulation of the ABO gene is reported and its relationship to common alleles at this locus defined.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Olsson, Martin L, et al.
(författare)
-
Heterogeneity of the blood group Ax allele: genetic recombination of common alleles can result in the Ax phenotype
- 1998
-
Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 8:3, s. 231-238
-
Tidskriftsartikel (refereegranskat)abstract
- The Ax phenotype is an important subgroup of the ABO blood group system. Its inheritance does not always follow Mendelian rules and recent studies suggested that different alleles can result in this phenotype. This suggestion has been explored by cloning and sequencing exons 6 and 7 of the ABO gene and the intervening intron from members of six unrelated families expressing the Ax phenotype. Two families showed the previously described T646A 'Ax' mutation as the only deviation from the consensus A1 allele. In two other families the Ax phenotype was inherited as two different recombinational gene products. Combination of exon 6 derived from A or B/O2 alleles with exon 7 from the O1v allele created two novel alleles that have four O1v-characteristic nucleotide substitutions in exon 7, including T646A. Sequencing and analysis of polymorphisms in intron 6 defined the crossing-over zones of these hybrid alleles. Southern blot confirmed the hybrid formation by detecting ABO-related polymorphisms approximately 1.35 kb downstream from the ABO reading frame. The remaining two families expressed the Ax phenotype via an allele having A2-specific mutations. Thus, a heterogeneous molecular background leads to the serologically defined Ax phenotype and may well explain the different modes of inheritance observed.
|
|
| 7. |
- Olsson, Martin L, et al.
(författare)
-
Polymorphism and recombination events at the ABO locus: a major challenge for genomic ABO blood grouping strategies
- 2001
-
Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 11:4, s. 295-313
-
Tidskriftsartikel (refereegranskat)abstract
- The blood group ABO gene codes for a glycosyltransferase that adds the ultimate monosaccharide to a glycoconjugate and forms the A or B blood group specific antigen. The DNA structure of the three major alleles of the human blood group ABO system was first described in 1990. This review describes the subsequent developments, including the increasing number of variants of these common alleles and the underlying mutations thought to be responsible for the occurrence of some of the weak subgroups of blood group A and B. Several inactive (O) alleles are also now known. Our knowledge of the DNA sequence of the normal A and B alleles and of the rare and intriguing cisAB and B(A) phenotypes has resulted in plausible explanations for these. Allelic variations outside the translated exons have been investigated and resulted in detection of lineage-specific intron mutations and the discovery of an enhancer VNTR region affecting the rate of transcription at this locus. The occurrence of hybrid alleles can also explain hitherto abnormal inheritance in some pedigrees. The detection of hybrid alleles has been made possible by the presence of numerous polymorphisms found in the various ABO alleles. The role of chi (chi) sequences is discussed. Finally, the various genotyping methods available are summarized and their advantages and limitations are analysed in the light of the increasing allelic variation.
|
|
| 8. |
- Widell, Anders, et al.
(författare)
-
Detection of hepatitis C core antigen in serum or plasma as a marker of hepatitis C viraemia in the serological window-phase.
- 2002
-
Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 12:2, s. 107-113
-
Tidskriftsartikel (refereegranskat)abstract
- A new immunoassay for the detection of hepatitis C core antigen (HCVcoreAg) in peripheral blood during serological window-phase was evaluated among healthy blood donors, commercially available hepatitis C virus (HCV) seroconversion panels and in-house specimens from individuals undergoing seroconversion. Among 1964 low-risk blood donor samples, seven samples were initially reactive but only one was repeat reactive. Reactivity of this specimen was not confirmable by neutralization with specific anti-HCV core antibody, and the sample was negative for HCV RNA by polymerase chain reaction (PCR). The specificity of the HCVcoreAg enzyme-linked immunosorbent assay (ELISA) was 99.95%. In seven commercially available HCV seroconversion panels, HCVcoreAg appeared 23-46 days earlier than anti-HCV antibody by third generation assay. Additional testing with specimens from patients undergoing anti-HCV seroconversion indicated that HCVcoreAg becomes undetectable by the present test format soon after the onset of antibody. This test may be considered as an alternative to nucleic amplification techniques (NAT) for blood donor HCV screening. Additional development of technology for detecting HCVcoreAg may be useful for patient diagnosis and therapy monitoring.
|
|
| 9. |
|
|
| 10. |
|
|
