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Nowawadays we have methods which allow us to overcome hemolytic disease of newborn or to prevent it to onset. The Rh or Kell conflict, but how is it possible that it is present? Why it haven't disappear due to natural selection?

A hemolytic disease occurs for example when mother have Rh- and the unborn child have Rh+ after his father. Then when the blood of the child gets to mother circulatory system she creates anti-Rh+ antybodies which will attack and eventually kill her next baby with Rh+. Thus we can assume that hemolytic disease is genetically dependent and cause lethal effect.

So i'm looking for any explanation. I know, that there can be none, i'm just asking.

Z-DNA
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    You should have a look at the post Origin, or source, of rhesus negative in human blood (and eventually at Any evolutionary explanation for human blood groups?) – Remi.b May 29 '17 at 21:12
  • Disclaimer: I know nothing about hemolytic disease. I would suspect that not all babies of Rh+ and Rh- parents suffer from hemolytic disease. Do you have any reason to think that the variation babies have Rh+ and Rh- parents to have the disease is due to genetic reason (or in other words, is the disease heritable among the subset of the population of interest)? – Remi.b May 29 '17 at 21:16
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    Yes, the first baby is "immune" to it, because due to that baby (to be more exacly due to the baby's blood during birth) mom start creating antibodies. If no blood gets to her sistem then there is no problem to the next Rh+ child. But if antibodies exists, then they can travel though placenta to the baby's body and attack him. The Rh is heritable so there is much bigger benefit in having Rh+ daughter. So yes, hemolytic disease as a disease isn't sctictly heritable, but the cause of it is but not as straight as typical genetic disease. – Z-DNA May 29 '17 at 21:25
  • Plenty of undesirable conditions haven't faded away. It's not lethal enough is a reasonable answer, since you already know the genetics. – anongoodnurse May 30 '17 at 01:31

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Hemolytic disease is not a genetic disease. It is a drawback of how the immune system works. In general, the overall benefits of having the immune system as it is right now are way higher than sporadic disadvantages, like the Hemolytic disease, that is why it is not counter selected. If instead of being a rare condition it would be a common one, then I would expect it to be indeed counter selected.

alec_djinn
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  • It is genetic. It's connected to the blood heriability. – Z-DNA May 29 '17 at 20:55
  • Well, I would not call it genetic. The mother makes antibodies against the blood cells of the fetus. If the mother is Rh+ and the father is Rh- and the fetus Rh is from the father, there is a chance of incurring in the disease. But being of any Rh type is not a genetic disease per se. I can't find any gene in the literature linked to the disease itself. But please link any study that suggest the opposite, I am not a master in this particular disease. – alec_djinn May 29 '17 at 21:09
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    "If the mother is Rh+ and the father is Rh- and the fetus Rh is from the father, there is a chance of incurring in the disease"... this is completely wrong. –  May 30 '17 at 05:26
  • @GerardoFurtado It was a quick example but please, can you tell me what is wrong? – alec_djinn May 30 '17 at 07:10
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    HD only happens when the mother is Rh-. –  May 30 '17 at 07:12
  • I see, I have swapped the Rh signs! The concept stays, it is not correct to call it a genetic disease, it's an immune disease. – alec_djinn May 30 '17 at 07:13
  • You cannot correct a comment after 5 minutes! –  May 30 '17 at 07:14
  • just figured that out :) – alec_djinn May 30 '17 at 07:14