Which of the following is associated with Down syndrome: March 2010
Ans. D: Decreased AFP level Alpha-fetoprotein is made in the pa of the womb called the yolk sac and in the fetal liver, and some amount of AFP gets into the mother's blood. In neural tube defects, the skin of the fetus is not intact and so larger amounts of AFP is measured in the mother's blood. In Down syndrome, the AFP is decreased in the mother's blood, presumably because the yolk sac and fetus are smaller than usual. Estriol is a hormone produced by the placenta, using ingredients made by the fetal liver and adrenal gland. Estriol is decreased in the Down syndrome pregnancy. This test may not be included in all screens, depending on the laboratory. Human chorionic gonadotropin hormone is produced by the placenta, and is used to test for the presence of pregnancy. A specific smaller pa of the hormone, called the beta subunit, is increased in Down syndrome pregnancies. Inhibin A is a protein secreted by the ovary, and is designed to inhibit the production of the hormone FSH by the pituitary gland. The level of inhibin A is increased in the blood of mothers of fetuses with Down syndrome. PAPP-A, which stands for pregnancy-associated plasma protein A, is produced by the covering of the newly feilized egg. In the first trimester, low levels of this protein are seen in Down syndrome pregnancies. It is impoant to keep in mind that even the best combination of ultrasound findings and other variables is only predictive and not diagnostic. For true diagnosis, the chromosomes of the fetus must be examined. Amniocentesis is usually carried out between the 14th and 18th week of pregnancy. CVS is usually carried out between the 10th and 12th weeks of pregnancy.
Raised PAPP-A level
Decresed beta-HCG level
Raised estriol level
Decreased AFP level