"I most certainly don't trust typology as such a great instrument..."
I don't either. I'm just curious.
Supposing the typology statistics are correct: it appears that there is something in introversion and intuition together in a personality that can create genius (not always):
"Moreover, if you encounter an INTJ (Introverted, iNtuitive, Thinking, Judging), there is a 37% probability that his IQ places him in the top 2 percent of the population. The probability is 20% for an INTP, 15% for an INFJ, and 8% for an INFP. These four types account for 66% of the high-IQ population but only 6% of the total population."
If there is indeed a link between genius and mental illness, then some of these mentally ill geniuses would be "IN" types (obviously).
Now the question is whether there is really a link between "IN" types and mental illness.