Which marker is elevated in cases of T21?

In cases of Trisomy 21 (T21), commonly known as Down syndrome, a specific marker that shows an elevation is inhibin A. This marker is part of the second trimester maternal serum screening process that assesses the risk for certain chromosomal abnormalities, including T21. Elevated levels of inhibin A can indicate an increased likelihood of Down syndrome, making it a significant factor in prenatal screening.

Inhibin A is a hormone produced by the placenta, and its levels are typically measured alongside other markers, like AFP (alpha-fetoprotein), PAPP-A (pregnancy-associated plasma protein A), and estriol during routine prenatal screening. The combination of these markers helps in determining the risk of chromosomal abnormalities in the fetus. Inhibin A's elevation is particularly noted in pregnancies affected by Down syndrome, thus serving as a valuable indicator during prenatal testing.

The other markers mentioned have differing associations in various contexts. Low AFP levels are generally associated with an increased risk of certain congenital conditions but do not specifically indicate T21. Low PAPP-A also suggests an increased risk for several chromosomal anomalies but is not exclusive to Down syndrome. Similarly, low estriol levels might indicate other potential concerns in pregnancy rather than being directly associated with the likelihood