Α-fetoprotein

Α-fetoprotein (AFP) is a protein that is produced primarily by the liver and yolk sac of a developing fetus. It is a major plasma protein in the fetus, but its levels decrease significantly after birth. AFP is used as a biomarker in various medical contexts, including prenatal screening and the diagnosis of certain types of cancer.

Structure and Function

AFP is a glycoprotein with a molecular weight of approximately 70 kDa. It is structurally similar to albumin, another major plasma protein. AFP plays a role in the transport of various substances, including bilirubin, fatty acids, and steroids.

Clinical Significance

Prenatal Screening

AFP levels are measured during pregnancy as part of the triple test or quadruple test to screen for certain developmental abnormalities such as neural tube defects (e.g., spina bifida) and Down syndrome. Elevated levels of AFP in maternal blood may indicate the presence of these conditions.

Cancer Diagnosis

AFP is also used as a tumor marker in the diagnosis and monitoring of certain types of cancer, particularly hepatocellular carcinoma (HCC) and germ cell tumors. Elevated AFP levels in adults can be indicative of these malignancies.

Measurement

AFP levels can be measured in blood samples using various laboratory techniques, including immunoassays. The interpretation of AFP levels depends on the context, such as the patient's age, sex, and clinical condition.

Related Conditions

• Hepatocellular carcinoma
• Germ cell tumor
• Neural tube defect
• Down syndrome

See Also

• Albumin
• Biomarker
• Prenatal screening
• Tumor marker