It is my understanding that other diseases can cause vitiligo and no the other way around. Vitiligo is not life threatening per my doctors.
Actually science is showing that Vitiligo is more of a deterrent for skin cancer. Because of the auto immune factor our immune disease fights off melanoma more than other people since it is over active. 30% of people with Vitiligo will have another auto immune disease. Of that 30% 20% of it is thyroid disease.
You are at higher risk for skin cancers from exposure to the sun because of not having the protection of pigment in the affected areas.
Vitiligo is caused by an autoimmune disease, and although not caused by the Vitiligo, you are at risk for other events caused by your immune system attacking your body. For instance, my immune system once attacked my right eye. It was very painful and nearly blinded me. I also have Hashimoto's. Doctors have explained to me that it's all related.