Does transfusion of Asian-type DEL red blood cells to D- recipients cause D alloimmunization?

In 2005, the late George Garratty asked readers of , “Do we need to be more concerned about weak D antigens?” His question was prompted by his observation that “… there have been increasing numbers of reports of patients who had been transfused with donor blood having ‘weak D’ or undetectable D (e.g., DEL) who made anti-D.” Garratty reviewed the complexity of the D antigen and its variants, case reports of anti-D after transfusion of weak D RBCs to D- recipients, and variable D typing results depending on selection of anti-D reagents. He noted that most available data were from Europe and concluded that “countries with larger Asian or African populations … need to relate to statistics in their own countries.” Garratty’s question can be answered only when data are available for the many different scenarios in which different categories of weak D RBCs have been transfused to D- recipients. In this commentary, we address one of these scenarios, namely, the potential risk of D alloimmunization when Asian-type DEL (*) RBCs are transfused to D- recipients in the United States. We suggest how this issue can be resolved by a focused study in pertinent communities in the United States.