Maternal serum and amniotic fluid levels of macrophage inhibitory cytokine 1 in Down syndrome and chromosomally normal pregnancies

OBJECTIVES: To measure maternal serum and amniotic fluid levels of macrophage inhibitory cytokine-1 (MIC-1) in Down syndrome and normal pregnancies, assessing the utility of MIC-1 as a prenatal marker of Down syndrome. METHODS: Stored serum from 64 Down syndrome and 399 control pregnancies, collected at 8 to 17 weeks of pregnancy, and stored amniotic fluid from 17 Down syndrome and 53 controls, collected at 15 to 19 weeks of pregnancy, were retrieved for analysis. MIC-1 was measured using an established in-house ELISA, blinded to sample type. RESULTS: In maternal serum, MIC-1 levels are not altered in Down syndrome in either the first or second trimester. Levels, expressed as median (95% CI) multiples of the median (MoM), in the Down syndrome cases and controls were 1.07 (0.9-1.1) MoM and 1.0 (0.95-1.03) MoM respectively. In amniotic fluid, MIC-1 levels were significantly decreased compared to controls, 0.52 (0.44-0.64) MoM versus 1.0 (0.85-1.08) MoM (p < 0.0001). CONCLUSION: MIC-1 is decreased in amniotic fluid but not in maternal serum in Down syndrome pregnancies. MIC-1 will not be useful as a prenatal marker of Down syndrome.