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

Abstract

Background: The C^w (RH:8), C^x (RH:9), and MAR (RH:51) antigens are encoded by alleles at the Cc locus of the Rh system, where C^w and C^x are considered low-frequency antigens and antithetical to the high-frequency antigen MAR. The frequency of C^w (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 C^w and C^x expressions, respectively.

Methods: We investigated 11,536 RhD+ Brazilian blood donors. All samples were phenotyped for D, C, c, E, e, and C^w . In the C^w + samples, a molecular analysis was performed to detect the nucleotide substitutions A122G and G106A, which determine the C^w and C^x antigens, respectively.

Results: C^w antigen was found in 110 (0.95%) samples in the following phenotypes: DC^w e/dC^w e (72/0.62%), DC^w e/DC^w e (30/0.26%), and DC^w e/DC^w E (8/0.07%). Among 110 C^w + 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.

Keywords: Cw/Cx antigens; RHCE alleles; Rh phenotypes; blood group; genotyping.