Pregnancy-Associated Plasma Proteins in Aneuploidy Testing
Summary
Pregnancy-associated plasma proteins, notably pregnancy-associated plasma protein A (PAPP-A) and the free β subunit of human chorionic gonadotropin (fβ-hCG), have become cornerstones of first-trimester aneuploidy screening. PAPP-A is a metalloproteinase released by placental trophoblasts into maternal circulation, with concentrations rising steadily in normal gestation but markedly reduced in trisomies, particularly trisomy 21, 18 and 13. Conversely, fβ-hCG levels typically peak at the end of the first trimester and are elevated in Down syndrome but decreased in Edwards syndrome. These proteins are measured as multiples of the median (MoM) adjusted for gestational age and maternal characteristics. Integration with ultrasonographic markers, such as nuchal translucency, and emerging cell-free fetal DNA assays has substantially improved detection rates while minimising invasive diagnostic procedures.
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Pregnancy-Associated Plasma Proteins in Aneuploidy Testing publication trend
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Technical terms
Pregnancy-associated plasma protein A (PAPP-A): A placental metalloproteinase whose serum concentration is reduced in common fetal trisomies.
Free β human chorionic gonadotropin (fβ-hCG): The free β subunit of the pregnancy hormone hCG, elevated in Down syndrome and measured in first-trimester screening.
Multiple of the Median (MoM): A normalised unit expressing an individual marker concentration relative to a population median adjusted for gestational age and maternal factors.
References
- Pattern of secretion of pregnancy-associated plasma protein-A (PAPP-A) during pregnancies complicated by fetal aneuploidy, in vivo and in vitro. Reproductive Biology and Endocrinology (2014).
- A link between high serum levels of human chorionic gonadotrophin and chorionic expression of its mature functional receptor (LHCGR) in Down's syndrome pregnancies. Reproductive Biology and Endocrinology (2005).
- Proteomic profile of serum of pregnant women carring a fetus with Down syndrome using nano uplc Q-tof ms/ms technology. The Journal of Maternal-Fetal & Neonatal Medicine (2017).
- Predictive Performance of a Seven‐Plex Antibody Array in Prenatal Screening for Down Syndrome. Disease Markers (2015).
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