alpha fetoprotein


α fe·to·pro·tein


alpha fetoprotein

/al·pha fe·to·pro·tein/ (fe″to-pro´tēn) a plasma protein produced by the fetal liver, yolk sac, and gastrointestinal tract and also by hepatocellular carcinoma, germ cell neoplasms, other cancers, and some benign hepatic diseases in adults. The serum AFP level is used to monitor the effectiveness of cancer treatment, and the amniotic fluid AFP level is used in the prenatal diagnosis of neural tube defects.

alpha fetoprotein

A protein encoded by the AFP gene on chromosome 4q25 that is produced by the yolk sac and liver during embryonic development and thought to play the same role as serum albumin in adults. It bind copper, nickel, fatty acids and bilirubin and occurs naturally as a monomer, homodimer and homotrimer. Alpha fetoprotein is typically measured in two contexts: during pregnancy, either in amniotic fluid or serum as a screen for neural tube defects or other developmental defects (see table); and in adults suspected of hepatocellular carcinoma or germ cell tumours—i.e., testicular, ovarian, and far less commonly, of the stomach and pancreas (for the latter two of which AFP has no practical diagnostic utility). 

AFP elevation in pregnancy 
• Cardiovascular—Fallot’s tetralogy. 
• CNS defects—Anencephaly, spina bifida, other open neural tube defects, hydrocephaly, cyclopia, microcephaly, sacrococcygeal teratoma.
• GI defects—Oesophageal and duodenal atresia with impaired foetal swallowing, omphalocele due to transudation, gastroschisis, pseudo-obstruction and short bowel.
• Hematology—Fetomaternal haemorrhage, hydrops fetalis.
• Immunodeficiency syndromes—SCID and/or ADA deficiency, combined T- and B-cell defects, ataxia-telangiectasia.
• Miscellaneous—Cystic hygroma, Turner syndrome, foetal demise, twin gestation, congenital nephrotic syndrome.

AFP is also increased in infants at high risk of foetal death up to 4–5 months after screening, regardless of the presence of neural tube defects or multiple gestations.
References in periodicals archive ?
Special staining demonstrated that only a very few tumor cells were positive for alpha fetoprotein, despite the markedly elevated level of alpha fetoprotein in her serum.
alpha fetoproteins or carcinoembryonic antigens) in these lesions.