Christelle De Mees¹, Julie Bakker², Josiane Szpirer¹ and Claude Szpirer¹

¹Université Libre de Bruxelles, Institut de Biologie et de Médecine Moléculaires, Rue Profs Jeener & Brachet, 12; B-6041 Gosselies (Charleroi), Belgium. ²University of Liège, Center for Cellular & Molecular Neurobiology, Avenue de l'Hopital 1, B36; B-4000 Liège, Belgium.

Abstract: Alpha-fetoprotein (AFP) is a well-known diagnostic biomarker used in medicine to detect fetal developmental anomalies such as neural tube defects or Down's syndrome, or to follow up the development of tumors such as hepatocellular carcinomas. However, and despite the fact that the protein was discovered almost half a century ago, little was known about its physiological function. The study of Afp knock-out mice uncovered a surprising function of AFP: it is essential for female fertility and for expression of normal female behaviors, and this action is mediated through its estrogen binding capacity. AFP sequestrates estrogens and by so doing protects the female developing brain from deleterious (defeminizing/ masculinizing) effects of these hormones.