[belmarca]

And "outliers" aren't necessarily exotic. Idiopathic disease isn't rare and difficult to diagnose.

[Gibbon1]

The problem is the fat tail of rare conditions is really wide because their are thousands of them.

Say there are 500 rare conditions with a rate of 2 per 100k per year. That means one out of 100 patients will develop one of those 500 in a given year.