Organic acid concentrations in amniotic fluid found in normal and Down syndrome pregnancies.

Organic acids were examined from normal and Down syndrome pregnancies to identify possible differences between the amniotic fluid from fetuses with Down Syndrome compared with that of normal fetuses. Amniotic fluids were obtained from prior amniocenteses. Forty-one normal and 22 Down syndrome specimens were assayed using gas chromatography/mass spectrometry. 5-hydroxycaproate, methylsuccinate, alpha-ketoglutarate, and adipate were significantly elevated in Down syndrome, suggesting riboflavin deficiency. Phenylpyruvate was also significantly elevated in fetuses with Down syndrome. Phenylpyruvate inhibits the metabolism of tetrahydrobiopterin, which is necessary for neurotransmitter metabolism. Elevated phenylpyruvate is consistent with previous research, suggesting a disturbance of tetrahydrobiopterin metabolism in Down syndrome. Organic acid markers for B2 deficiency are elevated in the amniotic fluid of fetuses with Down syndrome. Elevation of phenylpyruvate may impair neurotransmitter metabolism. Organic acid markers for B12 levels are not different between the Down syndrome and normal group.