Weak or partial D: Importance of molecular characterization of D variants

This case report presents first case of RHD*weak D type 9 in a 38-year-old Indian patient with severe osteoarthritis of the left hip joint scheduled for total hip replacement surgery. During routine blood grouping, an unexpected weak reaction with anti-D was observed. Serological characterization using an extended partial D typing kit characterized the variant as DV. The patient was successfully transfused with a O RhD negative compatible unit as per transfusion guidelines after surgery, without any observed transfusion reactions. The blood sample was sent to the ICMR-National Institute of Immunohematology, Mumbai, where molecular characterization revealed the presence of an RHD* 01 W.9 allele, as the underlying cause of weak expression of the RhD antigen. Serology can at best lead to the detection of the presence of a variant but characterization requires the help of molecular techniques.