I've got it. I had what I can only really describe as an anxiety attack and ripped out half an eyebrow, a quarter of the hair on my head, and all my eyelashes on one side of my face. At the time I was on medication for bipolor disorder (due to what I can only assume was a misdiagnosis because some symptoms of my dysphoria might easily be mistaken for the depressions and the "manic highs" can be those times I distract myself with normal activities) and so I blamed on side effects of Depakote and nobody questioned it. I had to go to school like that for far too long. My eyebrow never really grew back in right, and I'm pretty sure my hair receded a little in the area I ripped it out.
When I first started puberty I would habitually rip out the hairs "down there" every chance I got. Then the facial hair began to spread to the sides of my face and my neck. I've got a large bald patch on my neck, sparsely populated, yet always irritated, sore, and inflamed. I don't even notice most of the time that I'm doing it until there's blood everywhere.
Wikipedia tells me it's brought on by stress and anxiety, so I'm very hopeful it dissipates when I get my hands on some hormones, as my dysphoria is my leading cause of stress and anxiety.
I know a few cis people who are affected by trichotillomania too. I think it affects a large amount of people, but few people would likely admit it unless they knew there was a name for it. It may or may not have anything to do with our gender issues, it may effect all people in a mostly-equal ratio. We can't really know for sure without education, surveys, and statistics.