I know I know... "we can trust the list" but realistically we can't trust anyone.  So I am going with the Red John being a woman.  John Doe and Jane Doe  = male and woman.  Since Patrick is Jane and a male, therefore Red John is a woman :) Also, I remember the episode when Patrick and his father screwed up one family with a very very sick girl by selling a fake healing crystal.  Her blindness could be the consequence of her "survival".. Though she directly might not be the killer, so she has others to do her bidding...