There are lots of mutations now known which cause weak expression of the D antigen. Patients who have been found to be weak D, which traditionally wasn't associated with the production of alloanti-D have gone on to make alloanti-D, so the old adage of "weak D's don't make anti-D and partial D's do" does not hold water any more. As Malcolm states, Geoff Daniels' paper above describes the situation perfectly. Current BSH guidelines state that if the patient is found to be a weak D type 1,2 or 3 then they are to treated as D positive, as the evidence behind alloanti-D production in these weak D phenotypes is limited, and flawed in many cases. Therefore ANY OTHER WEAK/PARTIAL D should be called a D variant, and treated as D negative.
