Viganò et al. formed two hypotheses of autoimmune etiology of endometriosis [26]; on the one hand, autoimmunity can underlie endometriosis development without CTLA4-dependent predisposition; on the other hand, endometriosis is not associated with autoimmune etiology but can predispose the development of autoimmune reactions. Here, CTLA4 is linked to endometriosis.