Extended Typing of Common Erythrocyte Antigens in Tunisian Blood Donors and Its Usefulness in Transfusion Immunology

Extended RBC antigens typing is very valuable in transfusion immunology since it is highly recommended to ensure better transfusion practices and avoid transfusion-related complications and to establish registries for rare blood donors as recommended by the International Society of Blood Transfusion and World Health Organization.

A group of 236 Tunisian blood donors were genotyped for 19 common blood loci using the Sequence-specific primers polymerase chain reaction (SSP-PCR) method. The statistical analysis was done using the HaploView Software.

The study showed the dominance of the loci: RHCE*e, KEL*02, FY*02 and CO*01; and the absence of the homozygous state of the CO*02 allele. Furthermore, two complete linkage disequilibrium leading to the absence of the two alleles RHCE*C-RHCE*E (C-E) and FY*01N.01 (FY*Anull) were detected. Additionally, it appeared that approximately 91% of these blood donors are positive for the RHD gene; and all subjects who lacked the RHD exon 10 are homozygous for the RHCE*c and RHCE*e variants. The study also revealed that the RH1 negative blood cannot be universal to the Rh system because almost all RH1 negative donated blood is RH:-2,4,-3,5 (ccee), which may constitute a risk in some recipients carrying the anti-RH4 and/or anti-RH5 antibodies.

Considering that some donated RBC units may contain blood with very immunogenic phenotypes, great caution is required when transfusing some subjects, especially in emergency situations because it can be a step towards subsequent complex or multiple alloimmunization.