Studies performed on lactotroph pituitary adenomas highlighted aggressive behavior, especially in the male gender, when the expression of ERα was reduced [158,159,160,161,162,163,164], probably associated also with the expression of genes situated on chromosome X (CTAG2, FGF13, and VEGF) that influence the ER pathway [158]. The gene discussed is CTAG2; the disease is pituitary gland adenoma.