Estrogen also plays a role in the pathogenesis of Graves disease by modulating the autoimmune response.13 Graves disease is 5-fold more prevalent among women than men, reflecting the possible effect of estrogen.14 Differential expression of the estrogen receptor beta gene (ESR2) was confirmed recently by microarray and immunohistochemistry in patients with endometriosis.17 In addition, polymorphism of the ESR2 is associated with susceptibility to Graves disease.18 Thus, changes in ESR2 function might be a common link between Graves disease and endometriosis. This evidence concerns the gene ESR2 and endometriosis.