Alpha-fetoprotein (AFP)

Alpha-1-fetoprotein (AFP), also alphafoetoprotein or α1-foetoprotein, is a glycoprotein in mammals that is produced during human embryonic development in the course of pregnancy by the entodermal tissue and fetal liver, or in adults especially in tumor cells of the liver. Physiologically, alpha-1 fetoprotein has the function of a fetal transport protein, particularly transporting copper, nickel, fatty acids, and bilirubin in fetal blood plasma. AFP is structurally closely related to the transport proteins albumin, vitamin D-binding protein, and afamine. Production begins in the four-week-old embryo, is highest in the twelfth to sixteenth weeks, and stops almost completely after birth. In the adult, plasma levels are usually less than 40 ng/ml.