Multiple miscarriages in two sisters of Thai origin with the rare Pk phenotype caused by a novel nonsense mutation at the B3GALNT1 locus.

OBJECTIVES: To determine the genetic background underlying the Pk phenotype in two Thai sisters suffering from multiple spontaneous abortions. BACKGROUND: The P antigen is carried by globoside, an abundant glycosphingolipid in the red blood cell (RBC) membrane. Inactivating mutations in the 3-ß-N-acetylgalactosaminyltransferase gene (B3GALNT1) give rise to the rare Pk phenotype, which lack the P and PX2 antigens. Consequently, naturally occurring anti-P may cause recurrent miscarriages following the cytotoxic attack of the globoside-rich fetal portion of the placenta. METHODS/MATERIALS: P/P1/PX2/Pk antigens on RBCs and their corresponding antibodies were detected by haemagglutination and flow cytometry. The B3GALNT1 coding region was sequenced, and an allele-specific polymerase chain reaction (PCR) was developed. RESULTS: The two sisters had suffered 8 and 11 miscarriages, most of which occurred in the first trimester. Anti-P and anti-PX2 were identified in their plasmas, and the RBCs typed as P-PX2-Pk +, i.e. had the Pk phenotype. Sequencing revealed homozygosity for a nonsense mutation, c.420T>G, in B3GALNT1. This substitution introduces a premature stop codon, p.Tyr140Ter, which is predicted to abolish enzymatic activity. Screening of 384 Thai donors indicated an allele frequency of 0·13%. CONCLUSION: We describe a novel nonsense mutation (c.420T>G) in B3GALNT1 (GLOB*01N·13), which was added to the 12 alleles already known in the GLOB system.

A and B antigen levels acquired by group O donor-derived erythrocytes following ABO-non-identical transfusion or minor ABO-incompatible haematopoietic stem cell transplantation.

BACKGROUND AND OBJECTIVES: ABO-incompatible haematopoietic stem cell transplantation (HSCT) presents a challenge to blood component transfusion. The aim of this study was to investigate the weak blood group A or B antigen expression by donor-derived group O red blood cells (RBC) observed following transfusion or minor ABO-incompatible HSCT. In addition, in vitro experiments were performed to elucidate possible mechanisms underlying this phenomenon. MATERIALS AND METHODS: A sensitive flow cytometry assay for the semi-quantification of RBC A/B antigen levels was used to assess patient samples and evaluate in vitro experiments. RESULTS: Analysis of blood samples from patients, originally typed as A, B and AB but recently transplanted or transfused with cells from group O donors, revealed the A antigen expression on donor-derived RBC, ranging from very low levels in non-secretor individuals to almost subgroup Ax -like profiles in group A secretors. The B antigen expression was less readily detectable. In vitro experiments, in which group O donor RBC were incubated with (i) group A/B secretor/non-secretor donor plasma or (ii) group A/B donor RBC in the absence of plasma, supported the proposed adsorption of A/B antigen-bearing glycolipids from secretor plasma but also indicated a secretor-independent mechanism for A/B antigen acquisition as well as direct cell-to-cell transfer of ABO antigens. CONCLUSION: The in vivo conversion of donor-derived blood group O RBC to ABO subgroup-like RBC after transfusion or minor ABO-incompatible HSCT raises the question of appropriate component selection. Based on these data, AB plasma should be transfused following ABO-incompatible HSCT.

A novel B(weak) hybrid allele lacks three enhancer repeats but generates normal ABO transcript levels.

BACKGROUND AND OBJECTIVES: Weak expression of A/B histo-blood group antigens is often explained by single nucleotide substitutions at the ABO locus. However, hybrid alleles containing segments from different ABO alleles can result in unexpected phenotypes and may complicate genotype analysis. We investigated the basis of weak B phenotype in a referred sample. MATERIALS AND METHODS: A healthy young woman was serologically phenotyped as AB(weak) and RBCs were characterized by flow cytometry. All seven ABO exons, five introns plus the 5'-region including the CCAAT-binding factor/Nuclear Factor Y (CBF/NF-Y) binding enhancer were sequenced. ABO transcript levels were measured in fresh peripheral blood samples. Expression of B antigen was semiquantified following transfection of HeLa cells. RESULTS: A new B(weak) allele with 53G>T resulted in a characteristic pattern of moderately weakened B antigen expression on RBCs. Its sequence revealed a novel hybrid between O(2) [O03] and B [B101] alleles with a crossingover region in intron 4 as defined by allele-specific polymorphisms. B transcript levels were similar to normal controls despite the O(2) -related single CBF/NF-Y-binding 43-bp motif in the enhancer region. Expression of the glycosyltransferase including the O(2) -specific Arg18Leu substitution resulted in a slight decrease in B-antigen-positive cells. CONCLUSION: We describe here the first hybrid between an O(2) and a B allele and characterized the associated decrease in B antigen expression. Although it lacks three enhancer repeat units compared to common B alleles, the resulting transcript level was unaltered. This study challenges previous suggestions that the number of 43-bp motifs in the ABO enhancer determines transcription rates in erythroid cells.

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.

The health care learning organization.

To many health care executives, emphasis on marketing strategy has become a means of survival in the threatening new environment of cost attainment, intense competition, and prospective payment. This paper develops a positive model of the health care organization based on organizational learning theory and the concept of the health care offering. It is proposed that the typical health care organization represents the prototype of the learning organization. Thus, commitment to a shared vision is proposed to be an integral part of the health care organization and its diagnosis, treatment, and delivery of the health care offering, which is based on the exchange relationship, including its communicative environment. Based on the model, strategic marketing implications are discussed.

Covalent binding of proteins to grafted plastic surfaces suitable for immunoassays. I. Binding capacity and characteristics of grafted polymers.

A method for the introduction of chemically reactive groups onto polymeric surfaces, suitable for immunoassays, is described. The method, referred to as grafting, uses gamma irradiation from a 60Co source to initiate the free radical reaction. Polystyrene and polyvinyl chloride surfaces were grafted with crotonic acid and characterized with ESCA. 2 nmol/cm2 of carboxylic groups were added during the method. Increased hydrophilic properties of the carboxylated surfaces were recorded by contact angle measurements. The grafting reaction did not impair the optical quality of the polymers studied. Various proteins were covalently linked to the modified surfaces of microtiter plates and tubes by means of a water-soluble carbodiimide. A significantly enhanced total capacity and strength of binding to grafted surfaces was demonstrated as compared to passive adsorption of the proteins to untreated surfaces.

Hypothesis of an ovular regulation of pregnancy weight-gain.

A retrospective study of 127 twin pregnancies has been carried out, considering the relation between maternal weight-gain and zygosity of the ovum. At 28 weeks of gestation, the maternal weight-gain distribution goes on according to a bimodal curve, the analysis of which shows that each pike corresponds to one twin-pregnancy variety. Whatever the considered term might be (28-32-36 weeks), the maternal weight-gain is higher in DZ than in MZ pregnancies, and it should be pointed out that toxemic pregnancies, in each group, have nothing to do with this difference. This maternal weight-gain difference may reflect the known quality difference between MZ and DZ ova. The data lead to set up the more general hypothesis of an ovular regulation factor of the maternal weight-gain, in addition to classic data such as the own fetal weight, its annexes, and maternal diet.