RHD genotyping of serological weak D phenotypes among blood donors in Eastern Iran

Qualitative and quantitative alterations of the D antigen, including weak D and partial D phenotypes, may lead to hemolytic transfusion reactions and hemolytic disease of the fetus and newborn (HDFN). Among these variants, the Partial DLO phenotype is clinically significant due to its potential to induce anti-D formation upon exposure to RhD-positive red blood cells. This study aimed to determine, for the first time, the prevalence of RHD variants in eastern Iran.

Between October 2024 and October 2025, fifteen blood samples exhibiting weak D antigen expression from blood donors in eastern Iran were analyzed. Serological phenotyping for D, C, c, E, and e antigens was performed. Molecular assessment of RHD variant alleles was conducted using PCR-SSP, Real-time PCR, and DNA sequencing.

The analysis of samples with serologically weak D expression revealed three different partial D alleles. The highest prevalence was observed for the Partial DLO allele (80%), followed by the Partial type 11 allele (13.3%) and the Partial DV type 2 allele (6.7%). Additionally, the Partial DLO phenotype was predominantly associated with the DCce antigen profile, with fewer cases showing the DCe profile.

The high prevalence of the Partial DLO phenotype (80%) among weak D individuals despite being reported as rare in most populations worldwide highlights a potentially unique genetic pattern in eastern Iran. These findings underscore the importance of implementing molecular RHD genotyping to improve transfusion safety in this region.