Peripheral serum levels of TGF-β and soluble markers for hypoxia (HIF-1α) and angiogenesis (VEGF-A, sVEGFR2), significantly increased in adult forms of endometriosis [37,48,50], were similar in adolescents with and without PE (the main vs. comparison groups of this study). This evidence concerns the gene TGFB1 and endometriosis.