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

Abstract

BackgroundWra 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 fatal case of acute hemolytic transfusion reaction caused by anti-Wra: case report and review of the literature

“…[13][14][15] The prevalence of Wr a has been estimated to be 0.064 percent (1 in 1570) in Norwegian blood donors, 16 1 in 1000 in the British population, and 1 in 785 in the Spanish population. 17 In a study of Brazilian blood donors, 18 the prevalence of Wr a was estimated to be 1 in 1662. The authors found that the prevalence of anti-Wr a was 1 in 31, similar to that found in Spanish blood donors, but higher when compared with other studies.…”

Desenvolvimento de estratégia de genotipagem para discriminação de alelos antitéticos do sistema de grupo sanguíneo Diego utilizando pool de DNA

“…Não foram encontrados indivíduos de nenhuma das populações estudadas com fenótipos deduzidos Wr (a+b+) ou Wr (a+b-). Esse resultado já era esperado frente a altíssima frequência do alelo DI*02.04 que é de mais de 99% em todas as populações do planeta (REID; LOMAS-FRANCIS; OLSSON, 2012) e é inclusive reproduzido em outros estudos brasileiros (ARNONI et al, 2015;BIANCHI, 2016;LATINI et al, 2014;MUNIZ et al, 2015).…”