Frequency of Wra antigen and anti-Wra in Brazilian blood donors

AbstractBackgroundWra is a low-incidence antigen, which is antithetical to the high prevalence red blood cell antigen, Wrb. Anti-Wra is a naturally occurring antibody that is found in approximately 1–2% of blood donors. The aim of this study was to determine the frequency of Wra and anti-Wra in Brazilian blood donors.MethodsA total of 1662 Brazilian blood donors were molecularly analyzed using the SNaPshot methodology to determine the WR*A/B alleles and to predict the frequency of the Wra antigen. To detect the anti-Wra, samples from 1049 blood donors were analyzed using a gel test with Wr(a+) red blood cells. The serum was treated with dithiothreitol (DTT) to determine the immunoglobulin classes. Immunoglobulin (Ig)-G isotype classification was performed in a gel test using the IgG1/IgG3 card. A monocyte monolayer assay was employed to predict the clinical significance of IgG anti-Wra.ResultsOf the 1662 donors, only one sample had the DI*02.03 allele in heterozygous predicting the Wr(a+b+) phenotype. Anti-Wra was detected in 34 (3.24%) samples, 64.7% in females and 35.3% in males. Regarding the immunoglobulin class, eight (23.5%) cases of anti-Wra were classified as IgG and 26 (76.5%) as IgM. Of the eight cases of IgG anti-Wra, four were IgG1, two were IgG3 and three anti-Wra were not IgG3 or IgG1, and thus probably IgG2 or IgG4. The results of the monocyte monolayer assay showed that IgG anti-Wra might be of clinical significance.ConclusionThis study shows a very low frequency (0.06%) of the Wra antigen in Brazilian blood donors. Additionally, it shows that the frequency of anti-Wra in this population is higher than previously reported

A New Strategy To Identify Rare Blood Donors: Single Polymerase Chain Reaction Multiplex Snapshot Reaction For Detection Of 16 Blood Group Alleles.

As an alternative to phenotyping, large-scale DNA-based assays, which are feasible for high-throughput donor red blood cell typing, were developed for determination of blood group polymorphisms. However, high-throughput genotyping platforms based on these technologies are still expensive and the inclusion of single nucleotide polymorphisms and analysis of the alleles depend on the manufacturer's determination. To overcome this limitation and in order to develop an assay to enable the screening of rare donors, we developed a SNaPshot assay for analysis of nine single nucleotide polymorphisms related to antigens that are difficult to assess using conventional serology. The single polymerase chain reaction multiplex SNaPshot reaction was optimized to identify nine single nucleotide polymorphisms determining 16 alleles: KEL*3/KEL*4, KEL*6/KEL*7, DI*1/DI*2, DI*3/DI*4, YT*1/YT*2, CO*1/CO*2, DO*1/DO*2, DO*4, DO*5. We designed a single multiplex PCR with primers encompassing the blood group single nucleotide polymorphisms and performed an internal reaction with probe primers able to discriminate the alleles after fragment analysis. The SNaPshot assay was validated with 140 known alleles previously determined by PCR restriction fragment length polymorphism. We were able to simultaneous detect nine single nucleotide polymorphisms defining 16 blood group alleles on an assay based on a multiplex PCR combined with a single base extension using genomic DNA. This study demonstrates a robust genotyping strategy for conducting rare donor screening which can be applied in blood centers and could be an important tool for identifying antigen-negative donors and, therefore, for providing rare blood.12 Suppl 1s256-6

PREVALENCE OF GENETIC SUSCEPTIBILITY FOR CELIAC DISEASE IN BLOOD DONORS IN SÃO PAULO, BRAZIL

ABSTRACT Background Celiac disease is a permanent intolerance induced by gluten, which is expressed by T-cell mediated enteropathy, and has a high prevalence in the general population. There is evidence of a strong genetic predisposition to celiac disease. Objective To determine the prevalence of genetic markers HLA-DQ2 and HLA-DQ8 in blood donors from São Paulo and measure human recombinant tissue transglutaminase antibody IgA class in HLA-DQ2 and HLA-DQ8 positive donors. Methods A total of 404 blood donors from São Paulo city and Jundiaí were included in the study and signed the informed consent form. Information regarding diarrhea, constipation and abdominal pain in the last 3 months was collected. Determination of HLADQ2 and HLADQ8 alleles was performed in all participants and human recombinant tissue transglutaminase antibody class IgA was measured only in blood donors who presentedDQ2 and/or DQ8. Results HLADQ2 and/or HLADQ8 were positive in 49% (198/404) of subjects. Positive samples were associated with alleles DR3, DR4, DR7, DR11 and DR12. The most frequent genotype was DR4-DQ8, which was present in 13.6% of samples, followed by genotypes DR3-DQ2 and DR7-DQ2 with DQB1*02 in heterozygous, which were present in 10.4% and 8.7%, respectively. Eleven out of 198 positive donors (5%) were positive to human tissue transglutaminase test. Conclusion We observed a high prevalence of genetic markers for celiac disease, HLA-DQ2 and HLA-DQ8, in blood donors from São Paulo, similar to prevalence described in Europe. These findings show that the prevalence of celiac disease should not be rare in our country, but underdiagnosed

A new strategy to identify rare blood donors: Single polymerase chain reaction multiplex SNaPshot reaction for detection of 16 blood group alleles

Background. As an alternative to phenotyping, large-scale DNA-based assays, which are feasible for high-throughput donor red blood cell typing, were developed for determination of blood group polymorphisms. However, high-throughput genotyping platforms based on these technologies are still expensive and the inclusion of single nucleotide polymorphisms and analysis of the alleles depend on the manufacturer's determination. To overcome this limitation and in order to develop an assay to enable the screening of rare donors, we developed a SNaPshot assay for analysis of nine single nucleotide polymorphisms related to antigens that are difficult to assess using conventional serology. Materials and methods. The single polymerase chain reaction multiplex SNaPshot reaction was optimized to identify nine single nucleotide polymorphisms determining 16 alleles: KEL*3/KEL*4, KEL*6/KEL*7, DI*1/DI*2, DI*3/DI*4, YT*1/YT*2, CO*1/CO*2, DO*1/DO*2, DO*4, DO*5. We designed a single multiplex PCR with primers encompassing the blood group single nucleotide polymorphisms and performed an internal reaction with probe primers able to discriminate the alleles after fragment analysis. The SNaPshot assay was validated with 140 known alleles previously determined by PCR restriction fragment length polymorphism. Results. We were able to simultaneous detect nine single nucleotide polymorphisms defining 16 blood group alleles on an assay based on a multiplex PCR combined with a single base extension using genomic DNA. Discussion. This study demonstrates a robust genotyping strategy for conducting rare donor screening which can be applied in blood centers and could be an important tool for identifying antigen-negative donors and, therefore, for providing rare blood121s256s263sem informaçã