scholarly journals Invasive Trophoblast Antigen (Hyperglycosylated Human Chorionic Gonadotropin) in Second-Trimester Maternal Urine as a Marker for Down Syndrome: Preliminary Results of an Observational Study on Fresh Samples

2004 ◽  
Vol 50 (1) ◽  
pp. 182-189 ◽  
Author(s):  
Glenn E Palomaki ◽  
George J Knight ◽  
Marie M Roberson ◽  
George C Cunningham ◽  
Jo Ellen Lee ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Observational Study ◽  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
False Positive Rate ◽  
Serum Markers ◽  
Maternal Serum ◽  
Second Trimester ◽  
Preliminary Results ◽  
Hyperglycosylated Human Chorionic Gonadotropin

Abstract Background: Down syndrome screening is commonly performed in the US using maternal age and three or four second-trimester maternal serum markers that can identify up to 75% of affected pregnancies by offering diagnostic studies to 5% of women. Invasive trophoblast antigen [ITA; hyperglycosylated human chorionic gonadotropin (hCG)] is a promising marker that can be measured in urine or serum in the first or second trimester. We report preliminary results for urinary ITA in an ongoing observational study. Methods: Women undergoing second-trimester amniocentesis for reasons not associated with biochemical testing provided consent and a urine (and possibly serum) sample that was tested within a few days. Demographic and pregnancy-related information was collected, along with karyotype. Screening performance was modeled for ITA alone and in combination with serum markers Results: Twelve recruitment centers collected urine from 2055 women with singleton pregnancies between 15 and 20 weeks of gestation (2023 unaffected, 28 Down syndrome, and 4 pregnancies with other chromosome abnormalities). After correction for gestational age, urine concentration, and maternal race and weight, the ITA measurements were higher in women with a Down syndrome pregnancy (median ITA, 4.33 multiples of the median). At a 75% detection rate, the false-positive rate could be reduced by substituting ITA for hCG measurements (from 5.6% to 2.6% for the triple test) or by adding ITA measurements to existing combinations (from 3.3% to 2.0% for the quadruple test). Conclusions: Our data provide preliminary confirmation of the potential usefulness of urinary ITA measurements in detecting Down syndrome in a setting that simulates routine usage.

scholarly journals First Trimester Biochemical Screening for Trisomy 21: The Role of Free Beta hCG, Alpha Fetoprotein and Pregnancy Associated Plasma Protein A

1994 ◽  
Vol 31 (5) ◽  
pp. 447-454 ◽  
Author(s):  
K Spencer ◽  
D A Aitken ◽  
J A Crossley ◽  
G McCaw ◽  
E Berry ◽  
...  
Keyword(s):  
Chorionic Gonadotropin ◽  
Plasma Protein ◽  
Human Chorionic Gonadotropin ◽  
Trisomy 21 ◽  
False Positive Rate ◽  
Protein A ◽  
First Trimester ◽  
Serum Markers ◽  
Maternal Serum ◽  
Detection Rates

The potential efficacy of screening for trisomy 21 in the first trimester, using maternal serum markers α fetoprotein, free β human chorionic gonadotropin, unconjugated oestriol and pregnancy associated plasma protein A, was studied in an unselected population of women between the seventh and fourteenth week of gestation. Using a combination of α fetoprotein and free β human chorionic gonadotropin, 53% of affected pregnancies could be identified at a false positive rate of 5%. Unconjugated oestriol and pregnancy associated plasma protein A levels were lower in cases of trisomy 21, but their inclusion with other markers did not significantly improve detection rate. Monitoring the same pregnancies also in the second trimester showed that screening in the first trimester identified the same cases as in the second. We conclude that first trimester screening using free β human chorionic gonadotropin and α fetoprotein, is a viable possibility and will lead to detection rates in excess of 50%. Prospective studies are needed to confirm these observations.

scholarly journals Medians for second-trimester maternal serum α-fetoprotein, human chorionic gonadotropin, and unconjugated estriol; differences between races or ethnic groups

1997 ◽  
Vol 43 (2) ◽  
pp. 333-337 ◽  
Author(s):  
Peter A Benn ◽  
Jonathan M Clive ◽  
Roxanne Collins
Keyword(s):  
Down Syndrome ◽  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Maternal Serum ◽  
Second Trimester ◽  
Asian Populations ◽  
Adjustment Factors ◽  
Race Ethnicity ◽  
Patient Values ◽  
Unconjugated Estriol

Abstract Second-trimester maternal serum α-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) are routinely measured in screening fetuses at high risk for Down syndrome or open neural tube defects (ONTD). For test interpretation, individual patient values of these three analytes are related to population-derived median values. We evaluated data from >21 000 pregnancies to determine the extent of race-specific differences in median concentrations. For samples at most gestational ages, median AFP, hCG, and uE3 values for white, black, Hispanic, and other patients were all significantly different. Differences remained significant even when data were corrected for patient weights. For each analyte, the extent of the variation was not the same at different gestational ages. Differences in median values across race/ethnicity groups appear to have only a small impact in Down syndrome screening but it may be appropriate to use alternative sets of AFP medians or adjustment factors to AFP medians for some Asian populations receiving ONTD screening.

Four Years' Experience With an Interlaboratory Comparison Program Involving First-Trimester Markers of Down Syndrome

2010 ◽  
Vol 134 (11) ◽  
pp. 1685-1691
Author(s):  
Glenn E. Palomaki ◽  
George J. Knight ◽  
Geralyn Lambert-Messerlian ◽  
Jacob A. Canick ◽  
James E. Haddow
Keyword(s):  
Down Syndrome ◽  
Chorionic Gonadotropin ◽  
Plasma Protein ◽  
Human Chorionic Gonadotropin ◽  
Interlaboratory Comparison ◽  
Protein A ◽  
First Trimester ◽  
Nuchal Translucency ◽  
Second Trimester ◽  
Coefficients Of Variation

Abstract Context.—We initiated a voluntary, self-funded interlaboratory comparison program in the fall of 2005 because no proficiency testing program was available to laboratories in North America offering first-trimester, combined serum and ultrasound, Down syndrome screening. Objectives.—To evaluate the first 4 years of the interlaboratory comparison program against stated goals, to identify areas of concern, and to create new initiatives as indicated. Design.—Five serum samples are distributed 3 times a year to be tested for pregnancy-associated plasma protein A, human chorionic gonadotropin or its β subunit, and dimeric inhibin-A; participants convert these results into multiples of the median. Patient histories include nuchal translucency information that enables the calculation of the risk of Down syndrome. Also included are educational components linked to interlaboratory comparison program results. Assessment of integrated (first- and second-trimester markers) risks is accomplished by having participants combine interlaboratory comparison program results with their results from a second-trimester proficiency testing program administered by the College of American Pathologists. Results.—The precision profile for pregnancy-associated plasma protein A shows decreasing coefficients of variation with increasing pregnancy-associated plasma protein A concentrations and multiples of the median (25% to 11% and 30% to 15%, respectively). In contrast, coefficients of variation are a relatively constant 12% throughout the entire range of human chorionic gonadotropin results. On a logarithmic scale, the median coefficient of variation of the risk of Down syndrome is 9%. Conclusions.—Participants in the interlaboratory comparison program reliably measure analytes, compute multiples of the median, and calculate consistent Down syndrome risks. Assays for the measurement of pregnancy-associated plasma protein A are not standardized and are less precise than those for human chorionic gonadotropin. Participants calculate reliable median equations given sonographer-specific sets of paired crown-rump length and nuchal translucency measurements.

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