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M L Olsson

Publications and source records attributed to M L Olsson.

At least 19 recordsLinked to original sources
PubMed2005

A clue to the basis of allelic enhancement: occurrence of the Ax subgroup in the offspring of blood group O parents.

Apparent deviation from Mendelian rules of blood group inheritance is rarely observed. Blood group O parents with children expressing weak A subgroups have occasionally been described but not explained. A detailed serological investigation of such a family is described here. The ABO locus was analysed by PCR-ASP/restriction fragment length polymorphism genotyping and DNA sequencing. The propositus' RBCs were very weakly agglutinated with monoclonal anti-A but distinctly with polyclonal anti-A,B, i.e. typical for Ax. Serum anti-A1 (titre 4) and -B were present. Her parents' blood groups were both clearly O, with titres of serum anti-A1, and -A at 16 and 4, respectively. Adsorption/ elution studies demonstrated A antigen on the daughter's cells only. The ABO genotypes were: mother, AxO1; father, O1vO2; and propositus, AxO2. The Ax allele was an A1-O1v hybrid allele with a crossing-over breakpoint between positions 235 and 446 in intron 6 (Ax-4). Compared to the A1 glycosyltransferase, this allele predicts a protein with two amino acid substitutions (Phe216Ile and Met277Val) known to yield either weakly expressed or no A antigen on RBCs. This study suggests that the nature of the ABO allele in trans can influence A antigen expression, a phenomenon previously described as allelic enhancement (or reinforcement). Potential mechanisms for this are discussed.

ABO Blood-Group System↗
PubMed2005

Report of the First International Workshop on molecular blood group genotyping.

The use of molecular genetic technology for blood group typing is becoming routine procedure in many reference laboratories worldwide. A First International Workshop was organized on behalf of the International Society of Blood Transfusion (ISBT) and the International Council for Standardization in Haematology (ICSH). Thirty laboratories that provide a molecular diagnostic service participated in the workshop. Six samples were distributed: two represented DNA from transfusion-dependent patients for testing for multiple polymorphisms; two represented fetal DNA prepared from amniotic fluid for RhD, Rhc and K-testing; and two represented plasma from RhD-negative pregnant women for fetal RhD testing. Error rates varied from 0 to 11% for different polymorphisms. A consensus arising from discussion on the workshop results between participants at a feedback meeting and by e-mail has resulted in seven recommendations for molecular blood group genotyping. Further international workshops will take place every 2 years, with a more limited exercise being organized in the intervening years.

Blood Group Antigens↗
PubMed2005

Blood group genotype analysis for the quality improvement of reagent test red blood cells.

BACKGROUND AND OBJECTIVES: Reagent red blood cells (RBCs) for antibody detection should express certain important antigens as a double dose, that is, the donors must be homozygous for the corresponding alleles. Traditionally, dose is determined by serological typing and known allele frequencies. However, RHD zygosity cannot be predicted serologically owing to the absence of an antithetical antigen, and FY zygosity is confounded by two variant haplotypes, FY*0 and FY*X. Furthermore, lack of reagents hampers our ability to type for some clinically important antigen pairs such as Do(a)/Do(b). MATERIALS AND METHODS: Genomic DNA was isolated from reagent RBC samples. Established, validated methods were used to determine the RHD, FY, and DO genotypes. RESULTS: Three of 52 D+ samples gave results that differed from the predicted genotype: two presumed R(1)R(1) samples and an R(2)R(2) sample were shown to be R(1)r' and R(2)r'', respectively. Five of 59 samples that were from presumed homozygotes for either FY*A or FY*B were heterozygous, together with either FY*X (three samples) or FY*0 (two samples). Seventy-five samples tested for DO were DO*A/A (n = 14), DO*A/B (n = 39), or DO*B/B (n = 22). CONCLUSIONS: The results show that serologically determined RhD and Duffy phenotypes of reagent RBCs are unreliable and that antigens we thought were represented as a double dose were single dose. The addition of Dombrock genotyping provides information which is useful in antibody identification. We conclude that selected genotype analyses are a valuable quality assurance measure to ensure that reagent RBCs comply with national and international recommendations for test sensitivity.

ADP Ribose Transferases↗
PubMed2005

The Abantu phenotype in the ABO blood group system is due to a splice-site mutation in a hybrid between a new O1-like allelic lineage and the A2 allele.

BACKGROUND AND OBJECTIVES: Many phenotypic variations in the expression of blood group A have been explained by variations in gene structure, but unresolved samples are frequently encountered in the reference laboratory. Among ABO subgroups, A(bantu) has the highest frequency in a specified population. The molecular basis of this phenotype is now described. MATERIALS AND METHODS: Blood from Black donors phenotyped as A(bantu) was subjected to genomic ABO screening and direct sequencing of polymerase chain reaction (PCR)-amplified ABO exons 1-7 and introns 2-6. Total RNA was extracted and ABO cDNA was synthesized by reverse transcription (RT)-PCR. Control material comprised Black South African, Swedish, Jordanian and Brazilian blood samples with common phenotypes. RESULTS: Genomic ABO typing indicated the presence of an A(2) allele in each A(bantu) donor, in combination with an O allele. No previously reported mutations associated with weak A or B expression were found. Direct sequencing indicated the common A(2) sequence with a single nucleotide deletion (AGGT>AGT) at the exon 4/intron 4 junction, predicted either to disrupt the reading frame (resulting in a premature stop codon) or to cause erroneous splicing (resulting in the exclusion of exon 4 from the mRNA). O mRNA, but no transcripts from the A(bantu) allele, could be detected. Surprisingly, the splice-site mutation was also found in approximately 5% of O alleles in Black South Africans, but not in other blood donors, or in non-O(1) alleles. Utilizing intron polymorphisms, the A(bantu) allele was shown to be a recombination between a new allelic lineage (O(1bantu)) and A(2), with a cross-over region near exon 5. CONCLUSION: The A(bantu) phenotype is caused by an O(1bantu)-A(2) hybrid at the ABO locus.

ABO Blood-Group System↗
PubMed2005

Novel glycolipid variations revealed by monoclonal antibody immunochemical analysis of weak ABO subgroups of A.

BACKGROUND AND OBJECTIVES: The chemical basis of the subgroups of A is largely unknown. We used thin-layer chromatography immunochemical staining techniques together with a range of characterized monoclonal reagents to analyse glycolipids isolated from a variety of weak subgroups. MATERIALS AND METHODS: Glycolipids isolated from red cells collected from nine genetically defined individuals of the rare subgroups of A, including a novel A(3) allele (A(2) 539G>A) not described previously, were subjected to a highly sensitive thin-layer chromatographic immunochemical analysis. RESULTS: Semicharacterized monoclonal antibodies revealed that, in addition to the expected quantitative differences between common phenotypes and the weak subgroups, qualitative glycolipid differences (or at least an apparent qualitative basis), caused by major changes in the ratios of different structures exist. Specifically it was found that the weakest A-expressing samples (A(el) phenotype) appeared to express an unusual A structure in the 8-12 sugar region. Variable expression of several structures in one of the A weak samples were suggestive of novel blood group A structures. CONCLUSIONS: Although no structural characterization could be undertaken, the results are clearly indicative that the variant glycosyltransferases of the rare ABO subgroups are not only inefficient, but they may potentially synthesize novel ABO structures.

ABO Blood-Group System↗
PubMed2004

Autologous del(20q)-positive erythroid progenitor cells, re-emerging after DLI treatment of an MDS patient relapsing after allo-SCT, can provide a normal peripheral red blood cell count.

A 54-year-old RhD-negative male with del(20q)-positive myelodysplastic syndrome was transplanted with bone marrow from an HLA-identical RhD-positive sibling donor. Cytogenetic relapse was detected 21 months after stem cell transplantation (SCT), with reappearance of the original del(20q)-positive clone and reversion to recipient RhD-negative blood group. The patient received sequential donor lymphocyte infusions (DLIs), resulting in mild graft-versus-host disease and pure red cell aplasia. At 2 years post DLI, the patient remains in a stable condition, despite a dominance of recipient-derived erythro- and granulopoiesis originating in del(20q)-carrying progenitor cells. We conclude that reappearance of autologous erythropoiesis, upon relapse after allogeneic SCT, may be predictive of erythropenia after DLI and that re-emerging autologous del(20q)-positive erythropoiesis post DLI can provide a normal peripheral red blood cell count. Furthermore, in patients relapsing after blood-group-mismatched transplantation, a possible reversion to recipient blood group should be considered prior to blood transfusion or DLI.

Chromosome Deletion↗
PubMed2004

A novel blood group B subgroup: serological and genetic studies.

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.

ABO Blood-Group System↗
PubMed2004

Genetic heterogeneity at the glycosyltransferase loci underlying the GLOB blood group system and collection.

The aim of this study was to further explore the molecular genetic bases of the clinically important but rare blood group phenotypes p, P(1) (k) and P(2) (k) by analysis of the 4-alpha-galactosyltransferase (P(k)) and 3-beta-N-acetylgalactosaminyltransferase (P) genes responsible for synthesis of the related P(k) (Gb(3)) and P (Gb(4)) antigens respectively. Lack of these glycolipid moieties is associated with severe transfusion reactions and recurrent spontaneous abortions but also offers immunity against certain infectious agents. Blood samples from 20 p and 11 P(1) (k) or P(2) (k) individuals of different geographic and ethnic origin were investigated. DNA sequencing by capillary electrophoresis was performed following amplification of the coding regions in the P(k) or P genes. In the P(k) gene, nine novel and five previously described mutations were detected. One of the newly found mutations introduced an immediate stop, five shifted the reading frame introducing premature stop codons and three were missense mutations causing amino acid substitutions in conserved regions of the transferase. Four new and two previously described mutations in the P gene were found. Three of the novel alleles reported here carried nonsense mutations whilst the fourth allele had a missense mutation. The finding of 13 novel mutations in 14 alleles emphasizes further the genetic heterogeneity at the glycosyltransferase loci underlying the GLOB blood group system and collection.

Amino Acid Sequence↗
PubMed2002

Phenotype prediction by DNA-based typing of clinically significant blood group systems in Jordanian blood donors.

BACKGROUND AND OBJECTIVES: During the past 10 years several DNA-typing methods have been developed to complement routine serological typing for determination of polymorphisms in the ABO, RH, KEL, JK and FY blood group genes. However, the molecular basis of blood groups can differ widely between ethnic groups. The purpose of this study was to evaluate selected DNA-based methods for phenotype prediction in a population not previously investigated. MATERIALS AND METHODS: Blood samples from a random sample of Jordanian blood donors were collected and red cells isolated from these blood samples were phenotyped for common ABO (n = 150) and KEL/FY/JK (n = 90) antigens. RHD-negative and -positive donors were selected for RH typing (n = 120 and 30, respectively). DNA was prepared and blood group genotyping performed according to selected methods in current use. Discordant samples required further investigation by extended serology and DNA sequencing. RESULTS: The degree of concordance between phenotype and genotype was high, but some exceptions were noted. Two of 14 A2/A2B samples lacked all mutations associated with known A2 alleles of the ABO system. RH typing revealed four samples with the c(cyt48) marker, causing false-positive RHC typing. A single D-negative sample was positive for D-specific exon 10 markers. The RHD pseudogene was not found in the 150 donors tested. Nine samples revealed discrepancies that were associated with unknown silent or weakly expressing Fyb-like alleles. CONCLUSIONS: With the exception of the FY system, we conclude that the molecular background of the clinically important blood group antigens studied here is similar to that reported for Caucasoids.

Alleles↗
PubMed2001

Genomic analysis of clinical samples with serologic ABO blood grouping discrepancies: identification of 15 novel A and B subgroup alleles.

Since the cloning in 1990 of complementary DNA corresponding to messenger RNA transcribed at the blood group ABO locus, polymorphisms and phenotype-genotype correlations have been reported by several investigators. Exons 6 and 7, constituting 77% of the gene, have been analyzed previously in samples with variant phenotypes but for many subgroups the molecular basis remains unknown. This study analyzed 324 blood samples involved in ABO grouping discrepancies and determined their ABO genotype. Samples from individuals found to have known subgroup alleles (n = 53), acquired ABO phenotypes associated with different medical conditions (n = 65), probable chimerism (n = 3), and common red blood cell phenotypes (n = 109) were evaluated by ABO genotype screening only. Other samples (n = 94) from apparently healthy donors with weak expression of A or B antigens were considered potential subgroup samples without known molecular background. The full coding region (exons 1-7) and 2 proposed regulatory regions of the ABO gene were sequenced in selected A (n = 22) or B (n = 12) subgroup samples. Fifteen novel ABO subgroup alleles were identified, 2 of which are the first examples of mutations outside exon 7 associated with weak subgroups. Each allele was characterized by a missense or nonsense mutation for which screening by allele-specific primer polymerase chain reaction was performed. The novel mutations were encountered in 28 of the remaining 60 A and B subgroup samples but not among normal donors. As a result of this study, the number of definable alleles associated with weak ABO subgroups has increased from the 14 previously published to 29.

ABO Blood-Group System↗
PubMed2001

Intercellular adhesion molecule-4 binds alpha(4)beta(1) and alpha(V)-family integrins through novel integrin-binding mechanisms.

The LW blood group glycoprotein, ICAM-4, is a member of the intercellular adhesion molecule (ICAM) family expressed in erythroid cells. To begin to address the function of this molecule, ligands for ICAM-4 on hemopoietic and nonhemopoietic cell lines were identified. Peptide inhibition studies suggest that adhesion of cell lines to an ICAM-4-Fc construct is mediated by an LDV-inhibitable integrin on hemopoietic cells and an RGD-inhibitable integrin on nonhemopoietic cells. Antibody inhibition studies identified the hemopoietic integrin as alpha(4)beta(1.) Antibody inhibition studies on alpha(4)beta(1)-negative, nonhemopoietic cell lines suggested that adhesion of these cells is mediated by alpha(V) integrins (notably alpha(V)beta(1) and alpha(V)beta(5)). The structure of ICAM-4 modeled on the crystal structure of ICAM-2 was used to identify surface-exposed amino acid residues for site-directed mutagenesis. Neither an unusual LETS nor an LDV motif in the first domain of ICAM-4 was critical for integrin binding. ICAM-4 is the first ICAM family member shown to be a ligand for integrins other than those of the beta(2) family, and the data suggest that ICAM-4 has a novel integrin-binding site(s). These findings suggest a role for ICAM-4 in normal erythropoiesis and may also be relevant to the adhesive interactions of sickle cells.

Amino Acid Sequence↗
PubMed2001

Polymorphism and recombination events at the ABO locus: a major challenge for genomic ABO blood grouping strategies.

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.

ABO Blood-Group System↗
PubMed2001

The ABO blood group gene: a locus of considerable genetic diversity.

The blood group ABO gene shows considerable polymorphism in most of the 7 exons. Introns examined so far have also shown blood group-related polymorphisms, as has an upstream enhancer region. Several polymorphisms affect the specificity of the gene product (glycosyltransferase) and explain the occurrence of blood group A and B. Various lethal mutations result in blood group O. Other mutations are presumed to alter the activity rather than the specificity of the enzyme and result in weaker A and B blood group phenotypes. In total, 27 A alleles, 15 B alleles, 26 O alleles, and 4 AB hybrid alleles are described and surely more will surface in the near future. Variation in geographic/ethnic distribution of allele frequencies is discussed, along with the confusing nomenclatures currently in use.

ABO Blood-Group System↗
PubMed2000

Genomic characterization of the kidd blood group gene:different molecular basis of the Jk(a-b-) phenotype in Polynesians and Finns.

BACKGROUND: The clinically important Kidd (JK) blood group antigens are carried by the urea transporter in red cells. The rare Jk(a-b-) phenotype can be caused by homozygosity at the JK locus for a silent allele, JK: This phenotype has been recorded in many ethnic groups, but it is most abundant among people originating from the Polynesian Islands and Finland. The molecular basis for Jk(a-b-) is unknown in these populations. STUDY DESIGN AND METHODS: Blood samples from individuals of Swedish, Polynesian, and Finnish origin were collected and characterized by routine JK blood group serology and JK genotyping. Genomic DNA covering the exons and intervening introns of the JK gene coding region was amplified by polymerase chain reaction, and fragments were directly sequenced. RESULTS: Exon and partial intron sequences in the coding region of the JK gene were determined. Finnish and Polynesian Jk alleles were analyzed; the only deviations from consensus were a splice-site mutation (G-->A) in Polynesians, causing skipping of exon 6, and a T871C substitution predicted to disrupt a potential N-glyco-sylation motif (NSS-->NSP) in Finns. Methods for rapid detection of silent Jk alleles were developed for clinical application. CONCLUSION: Polynesians and Finns have two different molecular alterations in their Jk alleles, both of which can now be determined by polymerase chain reaction.

Alleles↗
PubMed1999

Allele-related variation in minisatellite repeats involved in the transcription of the blood group ABO gene.

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.

ABO Blood-Group System↗
PubMed1998

Genomic typing of the Kidd blood group locus by a single-tube allele-specific primer PCR technique.

The Kidd (JK) blood group system is clinically important in transfusion medicine. Alloantibodies to antigens in this system may be produced following blood transfusion or during pregnancy and can result in serious haemolytic transfusion reactions and haemolytic disease of the newborn (HDN). JK antigens on erythrocytes are carried by glycoproteins with the capacity to transport urea through cell membranes. cDNA complementary to mRNA transcribed at the JK locus was cloned in 1994. The molecular basis of the Jk(a)/Jk(b) blood group polymorphism was recently shown to be a single nucleotide substitution predicting an amino acid change (Asp280Asn) in an extracellular loop of the JK glycoprotein. After confirmation of the JK gene polymorphism we developed a rapid and robust technique for JK genotyping with allele-specific primers in a single-tube PCR. In addition, a 217 bp intron located at nucleotides 811-812 in the JK gene was found and sequenced. The genotyping test was validated with samples from 106 Caucasian Swedish and 13 Black South African random blood donors. Complete phenotype-genotype correlations were obtained. However, four Jk(a-b-) samples of Polynesian and Finnish origin typed as Jk(b)Jk(b). Potential use of the presented method can be predicted in clinical transfusion medicine including prenatal determination of the JK genotype in a fetus at risk for HDN caused by JK antibodies.

Alleles↗
PubMed1998

The Fy(x) phenotype is associated with a missense mutation in the Fy(b) allele predicting Arg89Cys in the Duffy glycoprotein.

The molecular basis of the three major alleles (Fy(a)/Fy(b)/Fy) of the Duffy (FY) blood group system has recently been established but the Fy(x) phenotype associated with weak expression of the Fy(b) and other FY antigens is poorly understood. In the Fy(x) genes of five unrelated British and Swedish donors with the Fy(a+b+weak) phenotype we found two missense mutations predicting amino acid changes Arg89Cys and Ala100Thr in the FY glycoprotein. The same mutations were found in two Fy(a-b+weak) samples from individuals of Swedish and Algerian origin. Their red blood cells showed a marked decrease in Fy(b), Fy3 and Fy6 expression measured by routine serology and flow cytometry. The rare FY genotypes Fy(x)Fy(x) and Fy(x)Fy were confirmed by family studies and DNA sequencing. Screening by allele-specific primer PCR (ASP-PCR) for these mutations among 100 Caucasian and 100 Black random blood donors indicated allele frequencies of 2.5% and 0% respectively. Ala100Thr alone was present in 33% of the Caucasians (but none of the Blacks) with no weakening of FY expression. A novel allele at the FY locus associated with the Fy(x) phenotype was studied. Mistyping of this weak Fy(b) antigen in clinical transfusion medicine may lead to delayed haemolytic transfusion reactions in immunized patients. A potential role for genomic typing is proposed.

Alleles↗