Inhibin A and pro‐αC inhibin in Down syndrome and normal pregnancies

Using two enzyme-linked immunosorbent assays specific for inhibin A and pro-αC inhibin, levels of the two proteins were assessed in maternal serum from 43 Down syndrome and 300 chromosomally normal pregnancies at 15–17 weeks' gestation. Compared to the control pregnancies, both inhibin A and pro-αC inhibin were significantly elevated in the Down syndrome pregnancies with median levels, expressed as multiples of the normal median, of 1·53MoM and 1·34MoM, respectively (P<0·001 and P=0·046 compared to controls). Levels of inhibin A and pro-αC inhibin were weakly but significantly correlated in both the control and the Down syndrome sera (r=0·25, P<0·0001; r=0·4, P=0·008, respectively). These data suggest that the mechanism(s) underlying the elevated inhibin levels observed in Down syndrome may affect the regulation of both the inhibin α- and βA-subunits. Copyright © 1998 John Wiley & Sons, Ltd.