Low Prevalence of HLA-G Antibodies in Lung Transplant Patients Detected using MAIPA-Adapted Protocol.

Lung transplantation is often complicated by acute and/or chronic rejection leading to graft-function loss. In addition to the HLA donor-specific antibodies (HLA-DSA), a few autoantibodies are correlated with the occurrence of these complications. Recently, antibodies directed against non-classical HLA molecules, HLA-G, -E, and -F have been detected in autoimmune diseases, like systemic lupus erythematosus. Non-classical HLA molecules are crucial in the immunological acceptance of the lung graft, and some of their isoforms, like HLA-G*01:04 and -G*01:06, are associated with a negative clinical outcome. The aim of this study is to determine the frequency of detection of HLA-G antibodies in lung transplant recipients (LTRs) and their impact on the occurrence of clinical complications. After incubating the cell lines SPI-801, with and without three different HLA-G isoform expression, with sera from 90 healthy blood donors and 35 LTRs (before and after transplantation), HLA-G reactivity was revealed using reagents from commercial monoclonal antibody immobilization of platelet antigen assay (MAIPA ApDIA®). Only one serum from one blood donor had specific reactivity against the HLA-G transduced lines. Non-specific reactivity in many sera from LTRs was observed with transduced- and wild-type cell lines, which may suggest recognition of an autoantigen expressed by the SPI-801 cell line. In conclusion, this study allowed the development of a specific detection tool for non-denatured HLA-G antibodies. These antibodies seem uncommon, both in healthy subjects and in complicated LTRs. This study should be extended to patients suffering from autoimmune diseases as well as kidney and heart transplant recipients.

Multiplex Lateral Flow Assay for Rapid Visual Blood Group Genotyping.

Conventional blood group phenotyping by hemagglutination assays, carried out pretransfusion, is unsuitable in certain clinical situations. Molecular typing offers an alternative method, allowing the deduction of blood group phenotype from genotype. However, current methods require a long turnaround time and are not performed on-site, limiting their application in emergency situations. Here, we report the development of a novel, rapid multiplex molecular method to identify seven alleles in three clinically relevant blood group systems (Kidd, Duffy, and MNS). Our test, using a dry-reagent allele-specific lateral flow biosensor, does not require DNA extraction and allows easy visual determination of blood group genotype. Multiplex linear-after-the-exponential (LATE)-PCR and lateral flow parameters were optimized with a total processing time of 1 h from receiving the blood sample. Our assay had a 100% concordance rate between the deduced and the standard serological phenotype in a sample from 108 blood donors, showing the accuracy of the test. Owing to its simple handling, the assay can be operated by nonskilled health-care professionals. The proposed assay offers the potential for the development of other relevant single nucleotide polymorphism (SNP) panels for immunohematology and new applications, such as for infectious diseases, in the near future.

First description of a D-CE-D hybrid gene on a weak D Type 2 molecular background.

BACKGROUND: RhD phenotypes that express a significantly reduced amount of RhD antigen per red blood cell may be mistyped as RhD-negative by standard serologic methods. The molecular identification of weak D Type 1, 2, or 3 carriers allows managing them as RhD-positive and, thus, rationalizes the use of RhD-negative stock units and the administration of Rh-immunoglobulin prophylaxis, avoiding unnecessary costs and possible side effects. STUDY DESIGN AND METHODS: One sample was investigated for confirming a D-C-E+c+e- phenotype. Rh phenotyping was performed with the microplate direct hemagglutination test. DNA array analysis was performed using the BeadChip wRhD kit, and the RHD gene was explored by sequencing to determine the molecular background associated with RhD-negative phenotype. RESULTS: Molecular investigations showed a lack of amplification of Exons 3 through 7 and c.1154G>T transversion in Exon 9, suggesting an RHD-CE-D composite on a weak D Type 2 background. We attempted to precisely identify the two recombination sites generating this hybrid allele. The 5' and 3' breakpoints were located in Introns 2 and 7, which showed concentration of mobile Alu sequences most likely involved in the RHD-cE(3-7)-weak D Type 2 allele. CONCLUSION: Altogether, we identified the first example of an RHD-CE-D large hybrid allele on a weak D Type 2 background associated with an RhD-negative phenotype. By investigating the RHCE-D breakpoint zones, we suggest a mobile element-mediated recombination.

New KEL*01M and KEL*02M alleles: structural modeling to assess the impact of amino acid changes.

BACKGROUND: The KELL antigens are carried by the well-folded and highly polymorphic glycoprotein KELL, belonging to the M13 family of metalloproteases. Anti-KEL, particularly anti-KEL1, are clinically significant. We retrospectively investigated genomic DNA from samples with uncertain KEL1 or KEL2 phenotype and identified six novel Kmod alleles. We then considered a model of the protein three-dimensional (3D) structure to assess the impacts of the amino acid changes. STUDY DESIGN AND METHODS: The 19 exons of the KEL gene were polymerase chain reaction amplified and sequenced. Modeling was performed using the experimental 3D structure of human endothelin-converting enzyme-1 in the presence of the metabolite phosphoramidon. RESULTS: We identified four novel KEL*01M alleles with amino acid substitutions p.Arg447Trp, p.Gly641Arg, p.Ala645Val, and p.Gly703Arg found buried within helices of the ectodomain catalytic lobe. We also revealed one new KEL*02M allele with p.Gly263Glu in contact with solvent (water) located within the second lobe of the ectodomain. One sample with c.575G>C transversion (p.Arg192Pro) on a KEL*02 background showed a weakened reactivity for KEL1. According to our 3D modeling, these amino acid substitutions may have a profound impact on the protein structure. CONCLUSION: This study is especially interesting with regard to the description of four new KEL*01M alleles. Indeed, to date only two KEL*01M alleles have been described and our data suggest a nonnegligible incidence of KEL1 variants. Serologic KEL2-negative results as well as any ambiguity implying either KEL1 or KEL2 in donors should always be confirmed by means of genotyping analysis and discrepancies between these methods require sequencing of KEL gene.

Genotyping of 28 blood group alleles in blood donors from Mali: Prediction of rare phenotypes.

We determined the frequencies of clinically relevant blood group alleles in 300 blood donors from Mali. Multiplex test based on xMAP technology was used to investigate six blood group systems (RH, KEL, MNS, FY, JK, DO, HPA) and complementary analysis were conducted for MNS and RH systems. Polymorphisms that affect the specificity of molecular tests leading to discrepant genotype results are discussed. Antigen expressions were predicted showing that 50% of donors expressed at least one traditional low prevalence antigen, and 11.6% lacked the ability to express at least one high prevalence antigen compatible with Dob-, HPA1a-, S-s-U-, Jsb-, RH:-31 and/or RH:-34 phenotypes.

RH diversity in Mali: characterization of a new haplotype RHD*DIVa/RHCE*ceTI(D2).

BACKGROUND: Knowledge of RH variants in African populations is critical to improving transfusion safety in countries with populations of African ancestry and to providing valuable information and direction for future development of transfusion in Africa. The purpose of this report is to describe RH diversity in individuals from Mali. STUDY DESIGN AND METHODS: Blood samples collected from 147 individuals self-identified as Dogon and Fulani were analyzed for Rh antigens and alleles. RESULTS: The most common RHD allele variant was RHD*DAU0. Five predicted partial-D phenotypes were attributed to RHD*DAU3 or RHD*DIVa. Neither RHD*DAR nor RHD*DIIIa was found. Investigation of RHCE revealed three predicted partial-e antigens encoded by RHCE*ce(254G) in trans to RHCE*cE. Regarding C antigen, 28 Fulani typed as C+ and 16 of 28 harbored at least one RHCE*Ce-D(4)-ce, two being homozygous and predicted to show a rare RH:32,-46 phenotype. A new RHCE*ceTI with replacement of Exon 2 by RHD (RHCE*ceTI(D2)) was identified in Dogon and was identified by inheritance study to be in cis to RHD*DIVa. These samples typed C- with anti-C polyclonal antibody and monoclonal antibodies (MoAbs) MS24, P3X2551368+MS24, and MS273, but positive with anti-RhCe MoAb-BS58. The same pattern was observed in sample with RHD*DIVa/RHCE*ceTI. CONCLUSION: Our survey indicated an uneven distribution of RH variant alleles between Dogon and Fulani, suggesting that study in well-documented cohorts is warranted. A high incidence of predicted partial-C phenotype encoded by RHCE*Ce-D(4)-ce was found in Fulani. Further study will also be needed to clarify the clinical significance of the new DIVa/ceTI(D2) haplotype encoding partial D and variant ce antigens.

Short duplication within the RHCE gene associated with an in cis deleted RHD causing a Rhnull amorph phenotype in an immunized pregnant woman with anti-Rh29.

BACKGROUND: The rare amorph Rhnull phenotype is caused by silent alleles at the RH locus and usually arises in consanguineous families. To date, only five molecular backgrounds have been identified in five unrelated families. Subjects with Rhnull red blood cells (RBCs) readily produce alloantibodies to high-prevalence Rh antigens. STUDY DESIGN AND METHODS: RBCs from a pregnant woman (G5P3) from Libya, with a positive indirect antiglobulin test were phenotyped by hemagglutination. RHD and RHCE genes were analyzed at the genomic level and mutation inheritance pattern was assessed in the patient's family. RESULTS: Hemagglutination testing showed a D-C-E-c-e- phenotype in the proposita associated with the presence of a high titer anti-Rh29 (4096). Molecular analysis revealed a deletion of RHD and presence of a novel RHCE allele with a 7-bp duplication in Exon 7. This duplication is predicted to introduce a frameshift after His350, a new C-terminal sequence, and a premature stop codon resulting in shortened predicted protein with only 402 amino acids. The mutated allele was found at homozygous state in the proposita and heterozygous state in her parents and one brother. CONCLUSION: This report describes a novel RHCE mutation causing the loss of RhCE antigen expression in association with RHD deletion, leading to an amorph Rhnull phenotype.

Synonymous nucleotide polymorphisms influence Dombrock blood group protein expression in K562 cells.

To gain further insight into ART4 (DO) gene alleles (DO*A, DO*JO1, DO*A-WL, DO*DOYA, DO*B, DO*B-WL, DO*B-SH-Q149K, DO*B-(WL)-I175N, DO*HY1, DO*HY2, DO*DOMR) and evaluate the impact of synonymous nucleotide polymorphisms on protein expression and mRNA accumulation of DO*A-HA, DO*A-SH and DO*B-SH alleles, human erythroleukaemic K562 cells were transducted with variant DO-lentiviral particles and analysed by flow cytometry and quantitative reverse transcription polymerase chain reaction. Monoclonal antibody (MoAb) detection of DO*A-HA and DO*JO1 transductants was lower than DO*A transductants, while detection of DO*A-SH, DO*A-WL and DO*DOYA transductants was higher. Variant DO*B alleles, i.e. DO*B-SH, DO*B-WL, DO*HY1, DO*HY2 and DO*DOMR, showed reduced MoAb binding. The unexpected modifications of protein expression of the DO*A-HA, DO*A-SH and DO*B-SH alleles that differ from the DO*A or DO*B alleles by a single synonymous polymorphism were abolished by reversion, thus implying involvement of these polymorphisms. Depending on the Leu208 codon used, detection level ranged from 1 to 4·14. In the variant alleles resulting from single synonymous polymorphism, mRNA accumulation correlated roughly with MoAbs detection levels, suggesting post-transcriptional regulation. Other than a few reports involving aberrant splicing, the experiments described herein provide the first evidence that synonymous nucleotide polymorphisms can influence Dombrock blood group expression. Such polymorphisms should be taken into account for molecular screening and potential impact on transfusion.

Heterogeneity of alleles encoding high- and low-prevalence red blood cell antigens across Africa: useful data to facilitate transfusion in African patients.

Ethnic variations in red blood cell (RBC) antigens can be a source of alloimmunization, especially in migrant populations. To improve transfusion safety in continental Africa and countries with African migrants, we performed RBC genotyping to determine allele frequencies coding for high- and low-prevalence antigens. A total of 481 blood samples were collected in ethnic groups from West, Central and East Africa. Molecular typing was performed using a polymerase chain reaction - reverse sequence specific oligonucleotide method. Results demonstrated no DI*1, DI*3, YT*2, SC*2, LW*7, KN*2 alleles in any sample and the CO*2 allele was rare. The frequency of LU*1 was comparable to that of European-Caucasians (2%) except in Biaka pygmies (8%). The frequency of CROM*-1 was high in Mbuti pygmies (13%). High frequency of KN*7 and KN*6 may reflect selection pressure in the countries investigated. Analysis of Dombrock allele patterns confirmed uneven distribution of the DO*1 and DO*2 alleles with high frequencies of DO*-4 and DO*-5 in all groups. Altogether, findings demonstrated extensive allele-frequency heterogeneity across Africa and suggested that knowledge of patient ethnicity gives information about the high-prevalence antigens that may be lacking. These data are medically useful to support transfusion care of African migrants living in countries where the majority of the population is from a different ethnical background.

A comprehensive survey of both RHD and RHCE allele frequencies in sub-Saharan Africa.

BACKGROUND: The RH system is one of the most polymorphic blood group systems with numerous allele variants affecting Rh polypeptides expression. This complexity is at the origin of difficulties for transfusion of African patients especially sickle cell disease patients requiring chronic transfusion therapy with high risk of immunization. As a complete survey of RH variants is lacking in African populations, we performed red blood cell genotyping to determine the type and frequency of RHD and RHCE alleles in sub-Saharan African populations. STUDY DESIGN AND METHODS: A total of 347 blood samples were collected from individuals of six nonpygmoid and three pygmoid populations. RH typing was performed using two single-tube multiplex polymerase chain reaction amplifications (BioArray Solutions, Immucor). RESULTS: All six sub-Saharan nonpygmoid populations exhibited constant variety in both type and frequency of aberrant RHD and RHCE alleles. Predicted partial RH1 (1.8%) and RH5 (0.9%) phenotypes were less than expected. Conversely, predicted partial phenotype RH2 (5.5%) was frequent. Data confirmed the high frequency of samples positive for the non-clinically significant RH10/RH20 antigens (39.5%) and revealed a high frequency of RH54 (DAK, 8.1%). The pygmoid groups showed higher percentages of predicted partial RH antigens and greater heterogeneity reflecting wide genetic differentiation. CONCLUSION: Our data show that frequencies of aberrant RHD and RHCE alleles were similar, irrespective of location and ethnicity. In view of the predicted frequencies and relative clinical significance of both private antigens and high-prevalence antigens absent, the most relevant assays for individuals of African descent in a transfusion setting are for 1) partial RH2 in the patient and 2) RH54 (DAK) in the donor.

RHCE*cE734C allele encodes an altered c antigen and a suppressed E antigen not detected with standard reagents.

BACKGROUND: The RH blood group system has many RHCE variant alleles that have arisen through gene conversion or nucleotide changes. Two probands, with red blood cells (RBCs) that were D+C+E-c+(w) e+ were sent to our laboratories to resolve the weak c expression. STUDY DESIGN AND METHODS: Hemagglutination tests were performed by automated and manual procedures. Genomic DNA analysis was performed by sequencing of Exons 1 to 10 of RHCE and RHD. RESULTS: The probands' RBCs did not react with standard monoclonal anti-E reagents from Bio-Rad, Diagast, DiaMed, Immucor, Ortho, and Quotient. The RBCs reacted variably with anti-c reagents from Diagast, DiaMed, Immucor, or Ortho and did not react with the Quotient anti-c reagent. Surprisingly, sequencing results of RHCE showed the presence of C/G at Position 676 (E/e polymorphism) and the association of the E polymorphism with a 734T>C transition in Exon 5 of the RHCE, encoding a Leu245Pro amino acid substitution in the mature RhcE polypeptide. Replacement of leucine 245 by proline in the eighth transmembrane domain of the RhcE protein may have a steric effect on the protein such that most anti-E reagents do not bind and the interaction between anti-c and c antigen is also affected. CONCLUSION: We report a novel RHCE*cE allele, RHCE*cE734C, which was assigned the provisional ISBT allele name RHCE*cE.14 or RHCE*03.14. It was found in two probands whose RBCs had weakened c expression and typed E- with conventional anti-E reagents. These data, once again, highlight the fact that the genotype does not always reflect the phenotype.

Characterization of novel RHD alleles: relationship between phenotype, genotype, and trimeric architecture.

BACKGROUND: RH1 is one of the most clinically important blood group antigens in the field of transfusion and prevention of fetomaternal incompatibilities. New variant RHD alleles are regularly identified and their characterization is essential to ensuring patient safety. STUDY DESIGN AND METHODS: Blood samples with uncertain RhD phenotypes not resolved by our first-line SNaPshot assay were sequenced for all 10 RHD exons. RHD zygosity was investigated. Flow cytometry was performed to determine RhD antigen density and epitope pattern. RESULTS: Seven novel RHD alleles were identified. Six, that is, RHD(T55P), RHD(A85G), RHD(G132R), RHD(G132E), RHD(D403V), and DAR(T203A), resulted from nucleotide polymorphisms. The seventh, that is, RHD(S182WfsX46), resulted from a 4-bp deletion that led to a reading frame shift and the appearance of a premature stop codon. Study of RhD expression of the first five alleles at hemizygous state showed greatly reduced antigen densities ranging from 50 to 618 antigens per red blood cell (RBC). DAR(T203A) was classified as a partial D antigen with a weakened reactivity profile similar to that of DAR. As expected, no D antigen was detected on RBCs carrying the RHD(S182WfsX46) allele. In parallel, RhD expression of RHD(G336R)/weak D type 58, RHD(F410V), and suspected RHD(1-9)-CE was determined to be less than or equal to 50 antigens per RBC. RhAG/RhD(2) trimer model supports the observed phenotypes. CONCLUSION: Although the frequency of the new RHD alleles presented herein is low, their phenotypic and genotypic description adds to the repertoire of reported RHD alleles. These data can be useful for optimization of molecular screening tools.

Five-Years Review of RHCE Alleles Detected after Weak and/or Discrepant C Results in Southern France.

Immunohematology laboratories are regularly facing transfusion issues due to serological weaknesses. Altered (partial) RH antigens account for most of them. In some situations, RHCE variant alleles are involved. Herein we present our three-step molecular exploration, with allele frequencies, that has efficiently untangled RH2 phenotype weaknesses and discrepancies in our 2017-2021 cohort. In the last 5 years, the PACA Corse EFS molecular platform received 265 samples from healthy blood donors or patients with C and C/e typing difficulties. The first-intention technique (DNA array and real time PCR for RHCE*CeRN research) detected RHCE variant alleles in 143 cases (54%). The RHCE alleles classically found in African populations were the most frequent, with RHCE*CeRN allele in 40 cases (15%) and (C)ces haplotype type 1 and 2 in 26 cases (10%). A "CE" effect haplotype was suspected in 56 cases, due to the uncommon DCE haplotype that may explain the low C expression. When there were no RHCE*Ce or RHCE*CE alleles, we then searched for RHD polymorphisms by DNA array. We detected the RHD*DAU5 and RHD*DIVa in 18 and 7 cases respectively, suggesting that C ambiguity is related to the presence of these alleles which has never been described with DAU5. If no variant RHCE and RHD alleles were detected, we finally sequenced the 10 exons of both RHCE and RHD genes according to the clinical context and found seven new RHCE alleles. Thus, this molecular strategy would improve the knowledge of RHCE variants' expression and, thus, optimize the transfusion management.

Identification of RHCE and KEL alleles in large cohorts of Afro-Caribbean and Comorian donors by multiplex SNaPshot and fragment assays: a transfusion support for sickle cell disease patients.

To lower the alloimmunization risk following transfusion in blacks, we developed two genotyping assays for large-scale screening of Comorian and Afro-Caribbean donors. One was a multiplex SNaPshot assay designed to identify ce(s) (340), ceMO/AR/EK/BI/SM, ce(s) , ce(s) (1006) and KEL*6/*7 alleles. The other was a multiplex fragment assay designed to detect RHD, RHDψ and RHCE*C and 455A>C transversion consistent with (C)ce(s) Type 1 and DIII Type5 ce(s) . Variant RHCE*ce alleles or RH haplotypes were detected in 58·69% of Comorians and 41·23% of Afro-Caribbeans. The ce(s) allele, (C)ce(s) Type 1, and DIII Type 5 ce(s) haplotypes were identified respectively in 39·13%, 14·67% and 4·88% of Comorians and 32·23%, 5·28% and 1·76% of Afro-Caribbeans. Genotypes consistent with partial D, C, c and/or e antigen expression were observed in 26·08% of Comorians and 14·69% of Afro-Caribbeans. No homozygous genotype corresponding to the RH:-18, -34, and -46 phenotypes were found. However, over 50% of genotypes produced low-prevalence antigens at risk for negative recipients, i.e., V, VS, JAL, and/or KEL6. One new variant RHCE*ce(s) (712) allele was identified. This is the first determination of variant RHCE and KEL allele frequencies. Results indicate the most suitable targets for molecular assay screening to optimize use of compatible blood units and lower immunization risk.

Weak D and DEL alleles detected by routine SNaPshot genotyping: identification of four novel RHD alleles.

BACKGROUND: Molecular RHD blood group typing is very efficient for managing donors and patients carrying any of the various molecular types of weak D and DEL. The purpose of the work was to develop a multiplex polymerase chain reaction (PCR) SNaPshot assay for simultaneous detection of weak D and DEL alleles that are prevalent in Europeans, Africans, and Asians. STUDY DESIGN AND METHODS: Preliminary profiling was carried out on single-nucleotide polymorphisms (SNPs) associated with 13 prevalent RHD alleles, that is, weak D Types 1, 2, 3, 4.0, 4.0.1, 4.1, 4.2, 5, 11, 15, and 17; RHD(IVS3+1g>a); and RHD(K409K). Multiplex PCR was used to amplify six RHD regions encompassing 14 SNPs. Identification was obtained by incorporation of the complementary dye single base at the 3'-end of each probe-primer. A prospective analysis was then carried out on 152 blood samples from patients (n = 53) and donors (n = 88) with equivocal RhD serology and pregnant women (n = 11). RESULTS: After validation, our SNaPshot assay allowed direct genotyping of 82.9% of samples overall and 100% of samples harboring weak D Types 1, 2, 3, and 4.1 alleles. In the remaining 17.1% of samples overall, sequence investigation allowed accurate genotyping. In addition, four novel RHD alleles were identified, that is, RHD(S256P), RHD(L390L), RHD(F410V), and RHD(IVS4-2a>g). CONCLUSION: The SNaPshot assay described herein is a helpful supplementary tool for resolving doubtful RhD serology. By allowing accurate identification of weak D and DEL alleles this assay should allow better management of the donors and the patients genotyped weak D Types 1, 2, 3, and 4.1 who can receive D+ blood units.

Hypoxia inducible factor 1alpha gene (HIF-1alpha) splice variants: potential prognostic biomarkers in breast cancer.

BACKGROUND: Hypoxia-inducible factor 1 (HIF-1) is a master transcriptional regulator of genes regulating oxygen homeostasis. The HIF-1 protein is composed of two HIF-1alpha and HIF-1beta/aryl hydrocarbon receptor nuclear translocator (ARNT) subunits. The prognostic relevance of HIF-1alpha protein overexpression has been shown in breast cancer. The impact of HIF-1alpha alternative splice variant expression on breast cancer prognosis in terms of metastasis risk is not well known. METHODS: Using real-time quantitative reverse transcription PCR assays, we measured mRNA concentrations of total HIF-1alpha and 4 variants in breast tissue specimens in a series of 29 normal tissues or benign lesions (normal/benign) and 53 primary carcinomas. In breast cancers HIF-1alpha splice variant levels were compared to clinicopathological parameters including tumour microvessel density and metastasis-free survival. RESULTS: HIF-1alpha isoforms containing a three base pairs TAG insertion between exon 1 and exon 2 (designated HIF-1alphaTAG) and HIF-1alpha736 mRNAs were found expressed at higher levels in oestrogen receptor (OR)-negative carcinomas compared to normal/benign tissues (P = 0.009 and P = 0.004 respectively). In breast carcinoma specimens, lymph node status was significantly associated with HIF-1alphaTAG mRNA levels (P = 0.037). Significant statistical association was found between tumour grade and HIF-1alphaTAG (P = 0.048), and total HIF-1alpha (P = 0.048) mRNA levels. HIF-1alphaTAG mRNA levels were also inversely correlated with both oestrogen and progesterone receptor status (P = 0.005 and P = 0.033 respectively). Univariate analysis showed that high HIF-1alphaTAG mRNA levels correlated with shortened metastasis free survival (P = 0.01). CONCLUSIONS: Our results show for the first time that mRNA expression of a HIF-1alphaTAG splice variant reflects a stage of breast cancer progression and is associated with a worse prognosis.See commentary: http://www.biomedcentral.com/1741-7015/8/45.

ABO blood group, glycosyltransferase activity and risk of venous thromboembolism.

INTRODUCTION: ABO blood group influence the risk of venous thromboembolism (VTE) by modifying A and B glycosyltransferases (AGT and BGT) activities that further modulates Factor VIII (FVIII) and von Willebrand Factor (VWF) plasma levels. The aim of this work was to evaluate the association of plasma GTs activities with VWF/FVIII plasma levels and VTE risk in a case-control study. MATERIALS AND METHODS: 420 cases were matched with 420 controls for age and ABO blood group. GT activities in plasma were measured using the quantitative transfer of tritiated N-acetylgalactosamine or galactose to the 2'-fucosyl-lactose and expressed in disintegration per minute/30 µL of plasma and 2 h of reaction (dpm/30 µL/2H). FVIII and VWF plasma levels were respectively measured using human FVIII-deficient plasma in a 1-stage factor assay and STA LIATEST VWF (Diagnostica Stago). RESULTS: A and B GT activities were significantly lower in cases than in controls (8119 ± 4027 vs 9682 ± 4177 dpm/30 µL/2H, p = 2.03 × 10-5, and 4931 ± 2305 vs 5524 ± 2096 dpm/30 µL/2H, p=0.043 respectively). This association was observed whatever the ABO blood groups. The ABO A1 blood group was found to explain~80% of AGT activity. After adjusting for ABO blood groups, AGT activity was not correlated to VWF/FVIII plasma levels. Conversely, there was a moderate correlation (ρ ~ 0.30) between BGT activity and VWF/ FVIII plasma levels in B blood group carriers. CONCLUSION: Work showed, for the first time, that GT activities were decreased in VTE patients in comparison to controls with the same ABO blood group. The biological mechanisms responsible for this association remained to be determined.