Genetic diversity of the RHD gene in blood donors from the Brazilian Central-West

The Rh blood group system is recognized for its complexity and its clinical importance in transfusion medicine. Antibodies against Rh antigens are associated with hemolytic transfusion reactions, autoimmune hemolytic anemia, and hemolytic disease of the fetus and newborn. The present study aims to characterize D antigens and assess their allele frequencies at the molecular level.

Molecular characterization of RHD variants was performed on blood donors from the Brazilian Central-West who presented atypical D typing results. Serological profiles of all identified RHD variant alleles were also analyzed using different anti-D clones.

Among the D-positive samples, 1.25% exhibited weak or discrepant agglutination during serological D typing. Most samples (67/103; 65%) were classified within the RHD*weak partial 4 cluster, followed by RHD*weak D type 3 (17/103; 16%). Lower frequencies were observed for RHD*weak D type 1 (2/103; 1.9%) and RHD*weak D type 2 (6/103; 5.8%). Furthermore, the rare RHD*weak D type 38 and RHD*weak D type 145 variants were identified. Analysis with different anti-D reagents showed that 52% of the samples had agglutination scores below 2+. Notably, 27% were classified as inconclusive, and 21% exhibited RhD serological discrepancies.

Atypical reactions in RhD serological testing indicate the presence of variant D antigens. The RHD*weak partial 4 allele was the most prevalent RHD variant in the Brazilian Central-West population. However, the identification of rare RHD*weak D variants, such as types 38 and 145, highlight the genetic diversity reflective of the region's multiracial composition. Understanding the distribution of RHD variants can improve transfusion support and inform future RHD genotyping strategies.