Placental alpha microglobulin-1 (PAMG-1)
Placental alpha microglobulin-1 (PAMG-1) was isolated in 1975 from amniotic fluid by D. Petrunin and was originally referred to as specific alpha-1 globulin of placenta.
PAMG-1 is present in blood and the amniotic fluid and cervico-vaginal discharge of pregnant women. The concentration of PAMG-1 in the amniotic fluid of pregnant women (2,000–25,000 ng/ml), however, is several thousand magnitudes higher than that found in their background cervico-vaginal discharge when the fetal membranes are intact (0.05–0.2 ng/ml). It has been found to be present in amniotic fluid in significantly high concentrations throughout all three trimesters of pregnancy.
Because of its contrasting concentrations in the amniotic fluid and background cervico-vaginal discharge of pregnant women, PAMG-1 proves to be an excellent protein marker for amniotic fluid. Detecting amniotic fluid via PAMG-1 becomes particularly important when determining whether or not fetal membranes are ruptured. Premature rupture of fetal membranes (or PROM as it is more commonly referred) occurs in roughly 10% of pregnancies and is one of the most common diagnoses associated with premature delivery and neonatal complications that requires admission to the NICU. Risks of neonatal complications as a result of PROM can include infection, preterm delivery, fetal distress, prolapsed cord, and abruptio placenta.
Today, the diagnostic capability of the PAMG-1 protein is used by an immunoassay that employs a series of monoclonal antibodies (MABs) to the PAMG-1 protein. This immunoassay detects the presence of PAMG-1 in the cervico-vaginal discharge of pregnant woman and has been shown to detect rupture of membranes with approximately 99% accuracy.
- D. Petrunin, et al., "Immunological Identification of Organ Specific alpha-1 Globulin of Human Placenta and Its Content in the Amniotic Fluid," in Akusherstvo i Ginekologiya, 1977, N 1, pp. 64–65, Moscow, USSR)
- Alexander JM, Cox SM. Clinical course of premature rupture of the membranes. Semin Perinatol 1996;20:369–374
- Cousins L, Smok D, Lovett S, Poeltler D. AmniSure Placental Alpha Microglobulin-1Rapid Immunoassay vs Standard Diagnostic Methods for Detection of Rupture of Membranes. Am Jour of Peri. 2005; Vol 22
- Philipson EH, Hoffman DS, Hansen GO, Ingardia CJ. Preterm premature rupture of membranes: experience with latent periods in excess of seven days. Am J Perinatol 1994; 11:416–419
- Mercer BM, Goldenberg RL, Meis PJ, et al. The Preterm Prediction Study: prediction of preterm premature rupture of membranes through clinical findings and ancillary testing. The National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Am J Obstet Gynecol 2000;183:738–745
- French JI, McGregor JA. The pathobiology of premature rupture of membranes. Semin Perinatol 1996;20:344–368