Expression profiles of amniotic fluid from human fetuses with Trisomy 18 and euploid controls

To understand the molecular mechanisms underlying the congenital anomalies observed in patients with Trisomy 18, we compared gene expression in uncultured amniotic fluid supernatant samples from second trimester fetuses with Trisomy 18 and from euploid controls. Analysis of differential expression using both individual-gene and gene-set or pathway methods indicated disrupted function in ion transport, MHCII/T-cell mediated immunity, DNA repair, G-protein mediated signaling, kinases, and glycosylation. Significant down-regulation of genes involved in adrenal development was also identified in the trisomic fetuses, possibly explaining both the abnormal maternal serum estriols and the pre- and postnatal growth restriction found in this condition. We compared expression in five female fetuses with confirmed metaphase karotypes 47, XX, +18 and six female controls (46, XX). The gestational ages of the samples ranged from 17 5/7 to 20 6/7 weeks.