Report of the fourth International Workshop on molecular blood group genotyping.

The fourth International Society of Blood Transfusion (ISBT) workshop on molecular blood group genotyping was held in 2010, with a feedback meeting at the ISBT Congress in Berlin, Germany. Fifty laboratories participated, 17 more than in 2008. Six samples were distributed. Samples 1-3 were DNA samples for all red cell blood group tests available to the participants. Of the 46 laboratories that tested these samples, 37 obtained completely correct results, although the extent of testing varied considerably. Sample 4, also a DNA sample, was an Rh problem in which RHDΨ and RHCE*ceCF were present, but the participants were only informed that the donor's red cells typed as positive with some monoclonal anti-D. Of the 42 laboratories that participated in this exercise, seven performed the sequencing necessary to obtain the correct result. Samples 5 and 6 were plasma samples from RhD-negative pregnant women, for foetal RhD testing. These were sent to 25 laboratories, and two incorrect results were reported. Overall, the level of accuracy was about equal to that of the previous workshop. The main conclusion for the last two workshops can be reiterated: with greater care and attention to detail, very high standards could be set for molecular blood group genotyping.