Frequency of RHD variants in Brazilian blood donors from Parana State, Southern Brazil.

The Rh blood group system is one of the most complex, polymorphic and immunogenic blood group systems in humans. Some individuals produce a weak or a partial D as a result of RHD and RHCE gene conversion events and RHD point mutations. Because the incidence of RHD variants differs considerably among ethnic groups, the objective of this study was to establish the frequency of blood donors carrying some weak and partial RHD, at the molecular level, in 400 blood donors from the North/Northwest of the state of Parana, Southern Brazil. Another 30 blood donors whose RhD typing results in serology were inconclusive were also included. In this mixed Brazilian population, the most frequent weak D types were 1, 4, 3 and 2 (frequencies of 4.35%, 2.32%, 1.46% and 0.29%, respectively; total of 8.41%) and partial D was found in 2.90% of samples carrying the RHD gene. For samples with inconclusive RhD typing, 53.33% of them presented weak and partial RHD, and 43.75% had concomitantly more than one RHD variant. Our results demonstrate the presence of Caucasian and African D variants. This knowledge can contribute to the safety of transfusion strategies in this ethnic admixture population.