Normal Physiology
- Alpha-Fetoprotein in pregnancy is produced by the yolk sac, fetal GI tract and liver
- It passes via the placenta to the maternal circulation
- It is similar in structure to albumin
- The AFP gene is located on the q arm of chromosome 4
High Alpha Fetoprotein
- Adults: Hepatocellular carcinoma (levels over 500 ng/ml) but 10% have normal levels and so Ultrasound often used in addition for screening for Hepatomas, acute viral or drug-induced hepatitis
- Children : Ataxia-telangiectasia
- Pregnancy: Neural tube defects, Multiple pregnancies, Ventral wall defects, Poor fetal growth, Eclampsia, Fetal loss
Low Alpha Fetoprotein
- Down's syndrome: Prenatal screening - low AFP is currently offered for prenatal screening for neural tube defects and, in conjunction with free β-hCG and unconjugated estriol, for Down's syndrome
- Germ cell tumours (nonseminoma) - In testicular cancer, a positive marker value is highly sensitive in indicating relapse or response to treatment