Evaluation of maternal serum dimeric inhibin a as a first‐trimester marker of down's syndrome

Abstract

While second-trimester prenatal screening programmes for Down's syndrome have become established in prenatal care, it would be advantageous to be able to offer screening in earlier pregnancy. To this end, we have evaluated a new potential maternal serum marker, dimeric inhibin A, as a possible first-trimester marker. Dimeric inhibin A was measured in prospectively collected maternal serum from 23 cases of Down's syndrome and matched chromosomally normal controls, at 11-13 weeks' gestation. Levels of this protein were significantly elevated in the Down's pregnancies compared with the control pregnancies. The median multiple of the normal median (MOM) for the Down's samples was 2.46 (95 per cent confidence interval: 2.11-3.26, P < 0.0001 vs. controls). These results suggest that dimeric inhibin A is a useful discriminator of Down's-affected pregnancies from normal pregnancies in the first trimester and that sensitive screening in combination with maternal age and other possible markers may be practicable in the first trimester.

Measurement of Inhibin and Activin in Early Human Pregnancy: Demonstration of Fetoplacental Origin and Role in Prediction of Early-Pregnancy Outcome1

“…The recent development of sensitive and highly specific ELISAs for inhibin A [2], inhibin B [1], inhibin pro-aC [3], and activin A [4] and their subsequent application have permitted important insights to be gained into normal [5][6][7] and abnormal pregnancies [8][9][10][11][12].…”

Second trimester screening for Down's syndrome using maternal serum dimeric inhibin A

“…Dimeric inhibin A has been reported to meet these criteria. [4][5][6][7][8][9][10][11] Inhibins are circulating dimeric glycoprotein hormones synthesised by the gonads and the placenta. The subunit can combine with one of two subunits ( A and B) to form inhibin A or inhibin B. Inhibin precursors are also present in maternal circulation.…”

Dimeric Inhibin A as a Marker for Down's Syndrome in Early Pregnancy

“…Further studies using a new assay specific for dimeric inhibin A ( ab A) have suggested a possible role for dimeric inhibin A as a screening marker, since elevated serum levels have been found in women with fetuses affected by Down's syndrome in both the first and the second trimesters. 28,29 In this study, we extended the investigation of inhibin A to a larger group of women with fetuses affected by Down's syndrome or trisomy 18 and compared its performance in screening with that of the established markers alpha-fetoprotein, intact human chorionic gonadotropin, and the b subunit of human chorionic gonadotropin.…”