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Comment by guerrilla | Hacker News Reader

I don't mean to be dismissive at all but if the probability of being born blind or schizophrenic is very low then isn't the probability of being born blind and schizophrenic very very low? Why is it really surprising that there haven't been any known cases yet when diagnosing the latter is relatively new and probably plenty of cases of the former are overlooked in populous poor countries?

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I remember seeing an article on hacker news before about this. Someone actually worked out the math and you're right: there's such an infinitesimally small chance of having both and there is likely zero connection between the two conditions.

I'd be interested in seeing the comment you're referring to.

I can find sources that suggest the rate of children being born blind is on the order of 1 in 10000 [1], and that the rate of schizophrenia is on the order of 1 in 1000 [2] (and the actual numbers in those articles are slightly larger).

Multiplying those, you'd expect 1 in 10 million people (conservatively) to have both. That means there should be a few tens of people with both in the USA, and a few hundred worldwide, if the conditions are independent.

[1] https://jamanetwork.com/journals/jamapediatrics/article-abst...

[2] https://journals.plos.org/plosmedicine/article?id=10.1371/jo...

I would expect that those born blind would receive much more frequent medical attention than average, but maybe this isn't actually true or doesn't translate to mental health diagnoses.

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