What is the rate of occurrences of Down syndrome in subsaharan African populations? Is it the same as in white European populations?
An interesting hypothesis came to my mind: Could it be that Down syndrome is the result of interaction of different dominant or recessive Neanderthal or Denisovan genes that European and Asian populations cary in small percentages?


1 Answer 1


See UN > stats Down Syndrome per country.

What the data says

I have not made a proper statistical test (as I am too lazy to reformat the data in anything convenient to perform a statistical test) but the prevalence seems to be consistently around 0.12499% all around the world with very very little variance. I doubt there is any significant difference in the frequency of birth that have down syndrome.

As @Markonionini rightly noticed, these estimates of prevalance are slightly far fetch extrapolation and the UN specifically advice to consider them with caution. It is probably the best data we have though.

The hypothesis seems improbable to me

Do you have any good rational behind your hypothesis? Down Syndrom is typically caused by de novo mutations and not due to standing genetic variation (Veltman and Brunner 2012) so your hypothesis seems rather implausible to me.

  • $\begingroup$ Well, seeing only white people having Down syndrome, made me think in this direction. Other than that, I have no other arguments for this hypothesis. $\endgroup$ May 19, 2017 at 15:14
  • $\begingroup$ Good answer. +1 Would also be weird to have this kind of ploidy polymorphism floating around in the population ... but this gives me an idea. $\endgroup$ May 19, 2017 at 15:17
  • $\begingroup$ @AlexDeLarge Thanks.... but now we all want to know your idea! $\endgroup$
    – Remi.b
    May 19, 2017 at 15:19
  • $\begingroup$ @Remi.b totaly! $\endgroup$ May 19, 2017 at 15:22
  • 2
    $\begingroup$ @Markonionini and Remi.b, I posted this following that idea. I hope it is not too unclear. $\endgroup$ May 19, 2017 at 16:25

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