In my science-fiction story, there is a vile scientist that creates a synthetical virus, because he wants to kill all humans of British and Irish ancestry all over the world.

This virus ONLY affects humans with a British and Irish variant of a gene responsible for skin colour: SLC24A5.

So, I wonder how could a virus ONLY affects humans of a certain ethnicity?

  • $\begingroup$ Rehashing Heinlein? Sixth Column wasn't a virus, but it was a race-specific weapon... $\endgroup$
    – Zeiss Ikon
    Aug 5, 2022 at 13:53
  • $\begingroup$ Might also have some elements of Greg Egan's "The moral virologist" gregegan.net/MISC/MORAL/Moral.html $\endgroup$
    – Murphy
    Aug 5, 2022 at 14:17
  • 5
    $\begingroup$ I'm unsure how you want us to answer this question. The virus reacts lethally in people with a certain gene and non-lethally otherwise. Do you want us to talk about the specific chemistry that the virus uses to differentiate between the two populations, and how that leads to a disproportionally lethal response in one population. From the level of detail in your Q it seems like any technobabble will suffice. What do you need us for. $\endgroup$
    – sphennings
    Aug 5, 2022 at 14:19
  • $\begingroup$ You should enjoy watching "The Last Kingdom". When you talk about "British", do you mean Saxons or Danes? (Or Britons, or Celts, and let's not even get into Scotland...) Lumping them together with the Irish could have gotten you into a bar fight on either side of the Irish Sea a hundred years ago. You can read about Cas-CRISPR for some ideas but biology doesn't know philosophy. Especially not racist philosophy. :) $\endgroup$ Aug 5, 2022 at 15:52
  • $\begingroup$ "Humans of British and Irish ancestry": There is no way to look at the genetic make-up of a human and tell whether they have British or Irish ancestry, or not. At best you may get a result like "it is more likely than not that the person has north-western European ancestry, at least in part". (Consider three famous Prime Ministers of the United Kingdom -- Benjamin Disraeli, David Lloyd George, and Winston Churchill. You cannot be more British than the Prime Minister, can you? What do they have in common genetically?) $\endgroup$
    – AlexP
    Aug 5, 2022 at 16:08

2 Answers 2


With great difficulty.

So, you start off with something like a complimentary RNA sequence. Something like CRISPR but instead of just chopping up the SLC24A5 gene at the target region it activates some other mechanism that does something nasty like produce a neurotoxin.

You can throw in some tech tech tech words around that but something so exact that can activate an arbitrary biochemical mechanism doesn't really exist currently so can't really be described

So lets talk effects.

The variant in question is rs1426654. It's responsible for a large fraction of the difference in skin pigmentation between western Europeans and other groups.

It's present in

99.6% of european people.

23.8% of native african people.

84% of south asian people.

99% of Ashkenazi Jewish people.


So it's not going to be very exact because the variant is not unique to europeans, if it kills people then it's going to be killing half the human population of the planet.

Any such mechanism might also be fragile, one mutation in the virus and suddenly it's targeting everyone else as well.


The princple of viruses is that they do not "live" the way bacteria do. A virus enters the host body by random chance and then "hijacks" the cells of the host to produce many copies of the virus. That makes the virus heavily dependent on the host. It must be able to use parts of a different species in the reproductive process.

So assume that the virus "latches" onto just your trigger sequence in part of the reproduction cycle. If the sequence is missing, the virus cannot reproduce. Is this description detailed enough for you?


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