Serological Weak Expression of D Antigen: A Retrospective Study of Blood Donors and Patients at a Teaching Hospital in Eastern India.

Background and objective RhD variants show altered D antigen expression, affecting their serological detection. Proper identification is crucial due to potential anti-D antibody formation. This study aimed to retrospectively analyze the frequency and characteristics of D variant cases encountered during RhD typing in both blood donors and recipients and the transfusion implications. Methods We conducted a retrospective analysis of the D variant involving all the donors and patients whose samples were tested for blood grouping. RhD typing was done using monoclonal anti-D reagents via conventional tube technique (CTT) and column agglutination technique (CAT). Weak reactions (≤ 2+) were retested with different antisera. Weak D (Du) testing was conducted on serologically negative RhD results in donors. D variants were suspected based on discrepancies between CTT and CAT, weak reactions with different antisera, positive Du testing in RhD-negative donors, or anti-D alloimmunization in RhD-positive individuals. Data are presented in numbers and percentages. The odds ratio (OR) determining the association between different blood groups and age groups with the D variant in the donor population was calculated. A p-value <0.05 was considered statistically significant. Results D variants were found in 0.11% of donors and 0.039% of patients, with 21.7% being females. In the patient population, all the D variant cases were from surgical patients with transfusion requests; three received RhD-negative units, while seven did not require transfusions. D variants were more common in adult donors (25-44 years), with an 8.5 times higher occurrence in the AB group compared to the A group. Conclusions The D variant has a high prevalence in eastern India. Regional centers should be equipped to accurately identify and differentiate D variants, enabling improved management and effective conservation of RhD-negative units.