Prevalence of Weak D among Blood Donors at a Tertiary Care Hospital in Srinagar, Kashmir

Background After ABO antigens Rh D antigen is the next most important in the field of transfusion medicine. Among different ethnic populations the prevalence of weak D phenotypes varies significantly. Weak D refers to reduced expression of D antigen on the red blood cells that require an extended testing with indirect antiglobulin test (IAT) to get detected. Clinical importance of weak D arises when labeling the donor and the patient, as the donor is labeled as D positive and the patient as D negative. Aim The study was conducted to determine prevalence of weak D among D negative blood donors in our population. Material and Methods The study was conducted in the Department of Immunohematology and Transfusion Medicine GMC, Srinagar over a period of 18 months from October 2015 to March 2017. It is a hospital based cross-sectional study. In our center all healthy blood donor samples were tested for ABO and Rh D typing by routine serologic methods (conventional tube technique, immediate spin method) using two anti D reagents, anti-D (IgM) monoclonal and a blend of anti- D IgM and IgG. The blood samples which were negative for agglutination by immediate spin method were further tested for weak D using IgG anti-D in the IAT phase with low ionic strength solution (LISS) / Coombs gel card. Results A total of 15680 donor blood samples were analysed for ABO& Rh blood grouping. Among the total 15680 samples 94.6 % (n =14833) were Rh-D positive& 5.4 % (n = 847) were Rh-D negative. All the Rh-D negative (847) samples were subjected to weak D testing. Of the Rh-D negative samples 0.2 % (2/847) were weak D positive and of all the test samples 0.01 % (2/15680) turned out to be weak D positive. Conclusion This study shows the prevalence of weak D antigen in our donor population who are representatives of Srinagar region of J& K. It also stresses the need to identify individuals with variant D (rather than weak D or partial D) and to inform them about their status as donors and recipients of blood/ or organs.