CTLA4 and autoimmune disease: However, our results are contrary to the frequently reported association of CTLA-4 genotypes with several autoimmune diseases.[17, 18] To date, several hypotheses have been proposed to define the etiology of vitiligo, some of which are based on the immunological pathogenesis evidences.[18–20] However, most of these immunological pathogenic reactions can also be a consequence of the disease rather than being a cause.[21] Therefore, it is possible that the autoreactivities observed in vitiligo arise in response to challenges to the immune system by non-immunological mechanisms.