Alpha fetoprotein

Alpha fetoprotein (AFP) is a protein that in humans is encoded by the AFP gene. The AFP gene is located on the q arm of chromosome 4 (4q25).

AFP is a glycoprotein that is produced in the liver, yolk sac, and gastrointestinal tract of the developing fetus. After birth, AFP levels decrease and by the first year of life, they are virtually undetectable in the blood of healthy individuals. However, elevated levels of AFP can be detected in certain pathological conditions.

Function

AFP is a major plasma protein produced by the yolk sac and the liver during fetal development. It is thought to be the fetal form of serum albumin. AFP binds to copper, nickel, fatty acids and bilirubin and is found in monomeric, dimeric and trimeric forms.

Clinical significance

Elevated levels of AFP in adults can be an indication of hepatocellular carcinoma or germ cell tumors. AFP is also used as a marker in the management of testicular cancer and in the diagnosis of neural tube defects in a developing fetus.

Diagnostic use

AFP is used in prenatal screening tests. If a pregnant woman has high levels of AFP, it may suggest that the baby has a neural tube defect. However, elevated AFP can also indicate other conditions, such as multiple pregnancies or a miscalculated due date.

In adults, an AFP test may be performed to detect liver diseases such as hepatitis and cirrhosis, as well as cancers of the liver, testes, or ovaries.

See also

• Tumor marker
• Hepatocellular carcinoma
• Neural tube defect