FREQUENCY OF RH-D NEGATIVE & WEAK D IN PAKISTANI POPULATION

Abstract

Introduction:The Rh blood group system is one of the most polymorphic and immunogenic blood group
systems in humans. The expression of its antigens is complex, among that Rh-D antigen is the most
important antigen because of its high immunogenicity. Molecular genetic of RHD gene revealed that weak
D antigen is a Rh-D phenotype that possesses less numbers of D antigen epitopes on surface of red cells.
These individuals usually labeled RhD -ve by conventional testing but when transfused to RhD –ve person,
it can elicit antibody production. Variableincidence of weak D worldwide,lack of awareness, proper data
& multi-ethnic population of our country propelled to analyze it.
Material and Methods:A cross-sectional study conducted from August 2012 to August 2014. Around
48,228 healthy blood donors were tested for RhD factor. Commercially available monoclonal anti-D sera
were used to detect Rh-D factor status. Individuals found negative with saline anti-D, were further
investigated for weak D antigen by using indirect Coomb’s technique (IAT).
Results:Among 48,228 healthy blood donors, 44853 (93%) were Rh-D factor positive while 3375 (7%)
were Rh-D factor negative. Among these, 3375 Rh-D factor negative individuals 27 (0.8%) were found
to be weak D positive.
Conclusion: Although frequency of weak D does not came high among our donors but is still significant
enough to advocate testing of weak D in routine for all Rh –ve donors & pregnant women in order to avoid
consequences of anti-D allo-immunization which can lead to serious hemato-pathological problem.