High prevalence of serological weak D phenotype and preponderance of weak D type 4.0.1. genetic variant in a Nigerian population: implications for transfusion practice in a resource-limited setting

INTRODUCTION: Prevalence of RhD negative phenotype in Nigeria is low; this leads to scarcity of RhD negative red cells for transfusion. Serological and molecular genotyping of RhD negative individuals for weak D types could reduce this scarcity. The aim of this study was to determine the serological prevalence and molecular types of weak D phenotypes among blood donors and pregnant women in Kano, Nigeria. METHODS: A total of 4482 blood donors and pregnant women from three hospitals in Kano were recruited. An indirect antiglobulin test was used to determine weak D phenotypes. Molecular genotyping was performed on genomic DNA from whole blood amplified by polymerase chain reaction sequence-specific primers (PCR-SSP) with agarose gel electrophoresis. RESULTS: The mean age of the participants was 26.50 ± 5.79 years. The prevalence of the RhD negative phenotype was 4.2% (189/4482). Of the 189 RhD negative phenotypes, 20 (10.6%) were weak D positive. Molecular genotyping of the 20 Weak D positive phenotypes revealed 15 (75%) weak D type 4, of which 11 were due to the RHD*09.03 and RHD*DAR3 (T201R, F223V) polymorphisms and 4, due to RHD* 08.01 and RHD* DFV polymorphisms; 2 (10%) were due to the 602 C>G polymorphism, while the remaining 3 (15%) constituted partial D or other rare weak D types. CONCLUSION: The prevalence of weak D positive phenotypes is high in this study; weak D type 4 is the most common RhD genetic variant. Routine serologic weak D testing of RhD negative blood and molecular genotyping should be encouraged in resource-limited settings.