The Rh blood group system and its role in alloimmunization rate among sickle cell disease and sickle thalassemia patients in Iran

Introduction The alloimmunization following blood transfusion can be life‐threatening. The Rh alloantibodies are one of the most common causes contributing to alloimmunization. This study aimed to evaluate the rate and causes of alloimmunization and to determine the Rh phenotypes and genotypes among sickle cell disease (SCD) and sickle thalassemia (Sβ). Materials and Methods Our study included 104 SCD and Sβ patients referring to Baghaei 2 Hospital of Ahvaz in 2019 using a non‐random simple sampling method. The blood samples were collected for Rh phenotypes, alloantibody screening and identification, and molecular tests. The SSP‐PCR and RFLP methods with the Pst 1 enzyme were used. Results The alloimmunization rate was 9.6% and 13.2% based on immunohematological tests and medical records, respectively. The main alloantibodies (90%) were anti‐Rh, and 40% of the patients had multiple alloantibodies. A significant correlation was found between gender and alloimmunization. The phenotypes of DCce (37.5%), DCcEe (24%), Dce (20.2%), and dce (5.8%) and genotypes of R1r (25%), R1R2 (20.2%), R1R1 (18.3%), and R1R0 (10.6%) were the most prevalent. The R1R2 was a frequent genotype in Sβ. Conclusion R0r′ and R1R0 genotypes were limited to our population in Iran. Due to the differences in RH genotypes between our population and others, the blood transfusion from other ethnicities increased our total alloimmunization rate. The alloimmunization is the problem in 9.6% of sickle cell disease (SCD) and sickle thalassemia patients. The increase in the rate of alloimmunization was due to Rh alloantibodies. The Rh genotypes were different among sickle cell disease and sickle thalassemia patients than other populations and R1r′ and R0R1 genotypes were limited to our population.