Frequency of weak rhesus d phenotype in rhesus d-negative blood donors in Congo brazzaville

Background: The Rhesus (RH) system is of major clinical importance due to the high degree of immunogenicity of its antigens, particularly the D antigen. There are different variants of the D gene (weak D, partial D and Del). Screening for the weak D antigen can prevent the risk of alloimmunisation in Rh D-negative recipients. The aim of this study was to estimate the frequency of the weak D phenotype in D-negative blood donors in the Congolese population. Material and methods: This study was carried out on rhesus-negative blood donors received at the various collection stations of the national blood transfusion centre (Brazzaville and Pointe-Noire), from 1er February to 31 November 2018. Sociodemographic data were collected from the blood donor's clinical form. ABO and RH blood groupings were performed using the opaline plate haemagglutination technique. The weak phenotype D was determined using the indirect Coombs assay with anti-human polyglobulin antibody. Results: A total of 73 Rh D negative blood donors were selected for this study (52 in Brazzaville and 21 in Pointe-Noire). The O-negative phenotype was the most frequent (n = 54; 73.97%). In the RH system, the ddccephenotype complex was the most common (89.04%). The frequency of the weak D phenotype was 19.18%, with men predominating (78.57%). This phenotype was predominantly found in blood group A donors (45.45%) and relatively found in groups B and O (12.5 and 14.81%, respectively). Conclusion: This study reveals a relatively high frequency of the weak D phenotype in Rh D negative blood donors in the Republic of Congo. Systemic screening for this phenotype in Rh-negative blood donors at blood transfusion centres should therefore be considered in order to prevent alloimmunisation.