Why does the HgbS antigen affect the Rh genotype (Ror)?

[bbs2k]

(Dear Og I had a moment of shear stupidity, read on)

In my blood tranfusion service lab I’ve begun to notice a trend that has me confused. Whenever we needed to get phenotypically matched red blood cells for sickle cell disease patients they always tend to be D+, C-, c+, E-, e+ (R0r)[Weiner]. This is odd because the when I search our blood supply we rarely have blood products that are Rh positive and C- E-. So usually we’ll just start searching for Rh negative units, of the majority are C- and E-.

Here is an excerpt of from an report in the medical journal Transfusion:

When queried about their use of (phenotypically) antigen-matched RBCs, most institutions provided at least partially antigen-matched RBCs to SCD patients prophylactically, before transfusion (78%). Only 9 percent of institutions did not provide further prophylactically antigen-matched RBCs even after a patient became alloimmunized. Table 3 describes the spectrum of antigens for which institutions provided phenotypically matched RBCs. Antigens in the Rh and Kell system represented the majority of antigen matching. More than 90 percent of institutions provided C–, E–, and K– RBCs prophylactically; use of c– and e– RBCs were less frequent (74 and 65%, respectively). Antigennegative units for other blood groups were used much less frequently.

I realize that the Rh antigens and the HgbS antigens are both on the membrane of the red blood cell, but I don’t understand genetically what links them. Why is sickle cell disease so commonly linked with this rarer phenotype in our general red blood cell inventory? Does anyone know if having sickle cell disease affects other red cell membrane antigens?
(FTR, the answer to this question is stupidly simple, and I just had a brain-blank moment early on into writing it.

:smack: :smack: :smack:

The only reason I am continuing to embarrass myself and posting it is because I had a theory that this would sink with no responses since it is not exactly the most interesting question. Hell, maybe someone will learn something)

I’m going to regret this. :: submit new thread ::

[KarlGauss]

This is mostly a WAG, but I wonder if two things might be operating here:

1. People with SSD tend to require lots of transfusions. So, if the minor blood group antigens aren’t matched before transfusion, it’s just a matter of time before they develop antibodies to them, thereby rendering future transfusions more difficult (i.e. more difficult to find compatible blood).

2. Obviously, SSD has a very restricted ethnic distribution. It is quite possible that the minor RBC antigens you mention tend to be more common in that ethnic group (thus giving the false appearance of an association between them and SSD when, in fact, the association is due to the common “ethnic source” between them).

[Antigen]

I snooped around a little bit and managed to find this abstract, which seems to show that Rh antigens aren’t necessarily associated with the HbS gene.

The fact that so many of your hospital’s SCA patients have the R[sub]0[/sub]r phenotype might just be statistics: the R[sub]0[/sub] haplotype is more common in the Black population (a population also much more likely to have the HbS mutation), and (I think) r is the most common haplotype overall (but I could be wrong). Put those together and statistically you’re probably more than likely to find a decent number of SCA patients who are lacking the C and E antigens.

(and what do you mean, nobody will answer because it’s boring? we med techs need to stick together!)