Characterisation of RHD and RHCE variations in blood donors from Jazan Province, Southwestern Saudi Arabia

Rh is among the most important and highly polymorphic blood group systems due to the proximity of the RHD and RHCE genes, which encode numerous highly immunogenic antigens. However, in areas of Saudi Arabia with a high prevalence of hemoglobinopathy, the molecular characteristics of RHD and RHCE variations are lacking. This study focuses on characterizing the allelic and genotypic distributions of RHD and RHCE blood donors in Jazan, Saudi Arabia.

All blood donors' records between June 2023 and December 2024 were reviewed. ID RHD XT was applied for 60 negative or weak RhD Saudi donors, while 354 Saudi and 110 non-Saudi donors received RHCE genotyping using the ID CORE XT.

RHD deletion accounted for 76.7% of the RhD-negative donors. RHCE*Ce (44.1%) was the most common RHCE allele in Saudis, followed by RHCE*ce (31.9%) and RHCE*cE (12.3%). Variant alleles including RHCEce*(733G), RHCEce*(733G,1006T), RHCE*ceAR, RHCE*ce(712G), and RHDr's-RHCE*ce(733G,1006T) were detected in 11.72% in Saudi and 7.73% in non-Saudi, while low- and high-frequency antigens V, hrS, VS, and hrB were observed in Saudis with frequencies of 21.8%, 97.8%, 24.8%, and 93.2%, respectively. RHCE*ce/RHCE*Ce was the most prevalent genotype (26.8%). The non-Saudi group displayed similar profiles, with RHCE*Ce (48.2%), RHCE*ce (30.9%), and RHCE*cE (13.2%). There were no significant differences between Saudi and non-Saudi allele or genotype distributions using Fisher's exact test.

The study represents the first molecular characterisation of RHD and RHCE alleles in Saudi Arabia, revealing marked allelic and genotypic diversity, with important implications for transfusion safety in the Jazan region, where hemoglobinopathies are prevalent.