Molecular study of Cw/Cx antigens and frequency of Rh phenotypes in southeast Brazilian blood donors

Background The Cw (RH:8), Cx (RH:9), and MAR (RH:51) antigens are encoded by alleles at the Cc locus of the Rh system, where Cw and Cx are considered low‐frequency antigens and antithetical to the high‐frequency antigen MAR. The frequency of Cw (RH:8) is approximately 2% in Caucasians, 1% in Black people, 4% in Finns, and 9% in Latvians. The aim of this study was to determine the frequency of RhD+ phenotypes in a population of southeast Brazilian blood donors and to perform a molecular study to distinguish the RHCE*Ce.08.01 and RHCE*Ce.09 alleles, responsible for the Cw and Cx expressions, respectively. Methods We investigated 11,536 RhD+ Brazilian blood donors. All samples were phenotyped for D, C, c, E, e, and Cw. In the Cw+ samples, a molecular analysis was performed to detect the nucleotide substitutions A122G and G106A, which determine the Cw and Cx antigens, respectively. Results Cw antigen was found in 110 (0.95%) samples in the following phenotypes: DCwe/dCwe (72/0.62%), DCwe/DCwe (30/0.26%), and DCwe/DCwE (8/0.07%). Among 110 Cw+ samples, 108 showed the A122G nucleotide substitution associated with RHCE*Ce.08.01 allele and 2 samples the G106A substitution associated with the RHCE*Ce.09.01 allele. Conclusion This study showed the prevalence of the RhD+ phenotype in the Brazilian population, and that through the molecular study, it was possible to differentiate the RHCE*Ce.08.01 and RHCE*Ce.09.01 alleles. The phenotype frequency was similar from Black people (1%) and different from Caucasians, Finns, and Latvians.