My sister has
type 1 but it seems to be a random genetic mutation. All of us were tested and none of us seem to have it.
She was quite angry after she found out. I remember seeing people with much more severe cases like yours when we visited groups but at some point she stopped going. I guess she didn't want to be confronted with it.
She decided on eating as little meat as possible and probably never having kids since pregnancy (and related hormones) seem to have an adverse effect on it. Meaning that during large hormonal changes she suddenly gets more bumps on her skin.