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Elevated second-trimester dimeric inhibin A levels identify Down syndrome pregnancies
K D Wenstrom1, J Owen, D C Chu
1Department of Obstetrics and Gynecology, University of Alabama at Birmingham 35233-7333, USA.
American Journal of Obstetrics and Gynecology
|December 16, 1997
Summary
Second-trimester maternal serum inhibin A is elevated in Down syndrome pregnancies. Replacing estriol with inhibin A in screening tests improves detection rates for Down syndrome.
Area of Science:
- Prenatal diagnostics
- Biochemical markers in pregnancy
Background:
- Down syndrome (trisomy 21) is a common chromosomal abnormality.
- Second-trimester prenatal screening typically involves multiple biochemical markers.
Purpose of the Study:
- To evaluate if second-trimester dimeric inhibin A serum levels can differentiate Down syndrome pregnancies from euploid pregnancies.
Main Methods:
- Enzyme-linked immunosorbent assay was used to measure inhibin A levels in stored maternal sera.
- Data from 40-50 euploid and 33 Down syndrome pregnancies (14-20 weeks gestation) were analyzed.
- Performance was assessed within a multiple-marker screening context, comparing inhibin A to estriol.
Main Results:
- Mean inhibin A levels were significantly higher in Down syndrome pregnancies (2.84 MMoM) compared to euploid pregnancies (1.22 MMoM).
- An inhibin A cutoff of 1.6 MMoM detected 70% of Down syndrome cases with a 22% false-positive rate.
- Substituting estriol with inhibin A improved Down syndrome detection rates while lowering the screen-positive rate.
Conclusions:
- Elevated second-trimester maternal serum inhibin A is a marker for Down syndrome pregnancies.
- Incorporating inhibin A into multiple-marker screening enhances diagnostic performance for Down syndrome.