Malaria and blood type

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The ABO blood group was one of the first genetic markers used in genetic anthropology, and the worldwide distribution of the various alleles was one of the first known for any locus. It also has a long history in medical genetics as a marker, and there are myriad associations of blood type to various diseases (many of these are probably spurious; see the introduction to the second article).

With that in mind, it was interesting to see this (properly done) study showing an association between type O blood type and reduced severity of malaria:

Malaria has been a major selective force on the human population, and several erythrocyte polymorphisms have evolved that confer resistance to severe malaria. Plasmodium falciparum rosetting, a parasite virulence phenotype associated with severe malaria, is reduced in blood group O erythrocytes compared with groups A, B, and AB, but the contribution of the ABO blood group system to protection against severe malaria has received little attention. We hypothesized that blood group O may confer resistance to severe falciparum malaria through the mechanism of reduced rosetting. In a matched case-control study of 567 Malian children, we found that group O was present in only 21% of severe malaria cases compared with 44-45% of uncomplicated malaria controls and healthy controls…This work provides insights into malaria pathogenesis and suggests that the selective pressure imposed by malaria may contribute to the variable global distribution of ABO blood groups in the human population.

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27 Comments

  1. That blood type map doesn’t look anything like a map of malaria infestation.

  2. malaria isn’t the only variable, but this suggests malaria is *a* variable.

  3. henry harpending had a paper about the distribution of group B. his site seems down now, but i think it is titled ‘spread of the B people’ or something.

  4. spread of the B people 
     
    Hmm. I’m a B person.

  5. the b people bisect eurasia. highest frequency runs from india straight north up through central russia. i’m an a person, but my dad is b, so i can empathize ;-) (mom is a, so i guess i’m ao).

  6. O is the universal donor whereas AB blood cannot be transfused into O, A, or B. It would make it seem that O is the original and that A and B are independent mutants. Selection for transfusion compatability was not a factor, of course; I don’t know what was, or whether it was selection rather than just drift. But you’d suspect that A and B each had some kind of independent positive effect. 
     
    Pure speculation on my part.

  7. Hmm. I’m a B person. 
     
    B+!

  8. I’m AB+ and have a B+ wife (all North/Western Euro ancestry) . Two kids are AB+, one’s AB neg, and one’s B+. I guess we’re staying away from the equatorial zones. The good news, being a universal recipient, is that “all your blood are belong to us”.

  9. I’m O+, my Dad is O- 
     
    My Mom is B+ as are most of her family, together with a few of my siblings. 
     
    Her family go back to Lancashire originally, to an area where there is > 20% B – supposedly due to the settlement there by the Romans of 5,500 Alano-Sarmatians.  
     
    Most of my Mom’s family, as I am, as also lactose intolerant too. 
     
    Most of my Mom’s family have very wide faces, with high cheekbones…

  10. David Boxenhorn 
     
    That blood type map doesn’t look anything like a map of malaria infestation. 
     
    Maybe it’s changed over time?

  11. Particularly interesting is the splotch of lower frequency in the highlands of Madagascar that presumably corresponds to the Merina.

  12. I am ab-negative. so rare i don’t exist. 
    I once read that ab blood type was only 1000 yrs old, but how can this be? Certainly As & Bs have been conmingling for longer than that.

  13. AB poz here. Mother: Ukrainian Jew (I guess, a B). Father, Polish Jew, A (right on his dog tags). Commingled in mid-20th century US.  
     
    Yes, I read that AB is only 1K years old; cooler heads must explain this.

  14. re: the age of the AB blood type. I’d never heard that 1K years figure, and it seems highly implausible– this paper suggests B arose (from the ancestral A) several million years ago: 
    http://mbe.oxfordjournals.org/cgi/content/abstract/14/4/399

  15. Rh-negative is recessive, and O is recessive. A and B together produce AB. 
     
    O negative, even though doubly recessive, is 7.7% of the U.S. population. O is the most comon single bloodtype, even though recessive. More than a third of all Americans are O, but only less than a sixth are RH negative. The 1/6 proportion seems constant over A, B, AB, O. 
     
    The map doesn’t make any sense to me. South America is pretty mixed in origin, but overwhelmingly O. The Americas are mixed, but extremely low in B. The Native American component shouldn’t be a factor for a recessive gene. The Latin American high-O zone seems to reach up into Georgia, which makes no sense at all. Northern Florida is much like the rest of the South. 
     
    It may be that there was an attempt to survey blood types of “original peoples” in given areas, but at this point in time that attempt would lead to highly conhjectural results.  
     
    I’d be reluctant to draw any conclusions from these maps.

  16. It may be that there was an attempt to survey blood types of “original peoples” in given areas, but at this point in time that attempt would lead to highly conhjectural results.  
     
    yeah. that is an original peoples map. i believe the blackfeet have a lot of A. most of the other NAs are O.

  17. btw everyone, the paper that p-ter linked to is Open Access (though a PDF). so if you are curious, read it dog!

  18. I guess that I’m skeptical of “original peoples” maps. My guess is that in the U.S. even the supposedly “pure” tribal members (not always the majority) have some inbreeding somewhere in the last 200 years.  
     
    Of course, if actual O predominance were found in actual populations, given that O is recessive it would be a very strong result. But if various corrections and extrapolations and selections had to be introduced it would seem weak. (The Blackfeet might just have interbred early on, while keeping mixed offspring within the tribe.)

  19. Boy, this thread seems to have brought the B (and AB) people out of the closet. Either that, or GNXP people disproportionately have the B allele!

  20. Either that, or GNXP people disproportionately have the B allele! 
     
    Some closet Finns in the bunch? :) 
     
    Apparently, Russian travel agencies have been advertising the city of Turku (SW Finland) to Russians on the basis that blood type B is more common there – iow, they have “Russian blood”. (desperate for ideas??) This was attributed to the Russian garrison there in 1800s. A Finnish geneticist did a back-of-the-envelope calculation and said that for this to explain the modest freq increase (17%->20%) each Russian soldier would have needed to beget at least 5 kids during his stay :)

  21. David Boxenhorn 
     
    That blood type map doesn’t look anything like a map of malaria infestation 
     
    Malaria used to be world wide. The last malaria epidemic in North America was less than a century ago and it was as far north as MN and WI at one time. 
     
    The same is true in Europe but modern vector control and the recognition of the way malaria is passed on eliminated it in these venues. 
     
    The last Yellow Fever epidemic (another mosquito born disease) was in New Orleans in 1912. When I was a medical student in the late 1960s I met some of the survivors. People used to move north of NO in the summer to avoid these diseases.

  22. “Most of my Mom’s family, as I am, as also lactose intolerant too.” 
     
    Would that have anything to do with them being B? According to the “eat for your blood type theory” type B arose 40,000 years ago, give or take a millenium, among pastoralists and are the premier lactose people, able to handle jugs of cream and hard cheese. However, these theories are laughed at by doctors, who as we know from history, are always right.

  23. Is there any special reason why Rh is not classified with A, B, and O? All 8 combinations of presence or absence of A, B, and Rh+ are found: O+, O-, A-, B-, O+, AB, A+, B+. and AB+.

  24. what do you mean? in this study?

  25. I’m just wondering why we don’t say A, B, C (=Rh+) and O. O would be the present O negative, and then you’d have A, B, C (O positive), AB, AC, BC, and ABC (AB positive).  
     
    Rh negative / positive do have a fairly uniform distribution, I guess, generally 5:1.  
     
    Just an off-hand question, not specific to the maps.

  26. the ABO blood group is determined by one locus, while the rh blood group is determined by another locus. the two are independent.  
     
    the duffy blood group is another, so if you wanted to include all the blood groups, you’d have to keep adding letters as you discovered them. probably simpler just to refer to each locus with a different notation.

  27. To me a flat notation would do the job better and be more expandable as more groups are discovered, at least for medicine and transfusion and for population and historical genetics. I suppose that at the molecular gene-chromosome level the present notation would probably be best.

a