RH VARIANTS IN BRAZILIAN PATIENTS WITH SICKLE CELL DISEASE (SCD) AND AFRICAN BRAZILIAN DONORS

Abstract

The transfusion therapy with packed red blood cells (RBCs) is a common practice on prevention and treatment of patients with SCD. However, RBC alloimmunization, especially against Rh antigens in patients with Rh variants, is still a challenge, as antibodies developed against these variants may have clinical significance. Knowing the prevalence of Rh variants can help in assessing the risks of alloimmunization and developing strategies to find compatible blood donors to chronically transfused patients. Based on this, our aim was to determine the occurrence of variant Rh alleles in patients with SCD undergoing regular transfusion and in African Brazilian blood donors to define a strategy for searching compatible blood for patients with Rh variants. Simultaneously, we analyzed 82 DNA samples of patients with SCD and 68 DNA samples of repeated blood donors self-declared as Afro descendants. All samples were genotyped using the HEA, RHD and RHCE BeadChip (Bioarrays, Immucor, USA) platforms. From the 82 patients with SCD evaluated, 21 (25.6%) had RH variant alleles, from which 6 (38.9%) were alloimmunized against Rh antigens. Thirteen patients (61.90%) had only RhCE variants, 5 patients (23.81%) presented only RhD variants and 3 patients (14.29%) had RhCE and RhD variants. The most common RHCE variant alleles found in patients were RHCE*ce733G and RHCE*ce S while the most common RHD variants were RHD*weak D type 4.0 and RHD*DAR. From the group of 68 blood donors analyzed, 25 (36.76%) had RH variant alleles. Three donors (12.0%) presented only RhCE variants, 20 donors (80.0%) had only RhD variants and 2 donors (8.0%) had both, RhCE and RhD variants. The most common RHCE variant alleles found in donors were RHCE*ce48C and RHCE*ce733G,1006T while the most common RHD variants were RHD*weak D type 2 and RHD*DAR. As for the RHD variant alleles, homozygous, heterozygous and compound heterozygous alleles were observed. As for the RHCE altered alleles found in patients and donors, we observed heterozygous variant alleles with wild type RHCE alleles, homozygous RHCE variant alleles and compound heterozygous alleles. Knowledge of Rh variants in recipients and donors can help to assess the risk of Rh alloimmunization and to develop an adequate strategy for selecting blood donors with compatible RH haplotypes.