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Reminds me of a donor we had once when I was a reference lab sup. He had donated 12 times as O NEG. The next time he donated, they picked up weak typing with Anti-A,B and with further testing, turns out he was a very weak subgroup of A! Unbelievable. I agree with A subgroup. I see a lot of people want to automatically classify the subgroup....but without further testing, that is actually erroneous. Best to just leave it at subgroup. Brenda Hutson, MT(ASCP)SBB

Yes, frequency, incidence and prevalence are all interchangeable with either "high" or "low" before any of them. For some reason (I know not why), low prevalence has suddenly become the "word of the day", but there is no particular reason for this (as far as I know). Those low prevalence antigens within the 700 series, and, come to that, the high prevalence antigens within the 901 series, are, as you say, placed there as they do not belong to any known blood group system. However, do not run away with the idea that all low prevalence antigens are in the 700 series, and all high prevalence antigens are in the 901 series. The antigen KREP, of the Diego Blood Group System has only ever been reported in one Polish individual and one Slovakian individual, and yet it is not in the 700 Series of antigens. Conversely, and as far as I know, DOLG of the Dombrock Blood Group System has only been found to be negative in one Sri Lankan woman, and yet is not in the 901 Series of antigens. This is because, in each case, the chromosome and the particular loci have been identified, and they are mapped to known areas of the genes which encode each of these antigens.

We used to do eluates but with the infrequency of need and competency challenges we decided to send to our reference lab. We request eluates on patients who need a transfusion (or investigating a TRRX) and are DAT + and who have been transfused within the past 14 days to rule out newly forming antibodies that could be completely absorbed onto the donor RBCs and may not be found in the plasma. Our reference lab has recently changed from 14 to 21 days post transfusion for eluate testing but we have not yet changed our rule. I believe the thought process behind this is that after 14 (or 21) days the newly formed antibody has had sufficient time to spill over into the plasma and can be identified in the ABSC/ABID. On patients that are transfused frequently we sometimes opt to give phenotypically similar blood for transfusion instead of sending out for an eluate with each transfusion event as this is time consuming and expensive.