Plasma homocysteine and methionine concentrations in children with neural tube defects

Mild to moderate homocysteinemia in women has been associated with an increased frequency of pregnancies with neural tube defects (NTD). Homocysteinemia is also an independent risk factor for premature vascular disease. In addition to folic acid, supplemental Vitamin B12, Vitamin B6 and betaine may normalize homocysteine metabolism, decrease the risk for NTD formation, and correct related metabolic imbalances in children with NTD. By means of automated amino acid analysis, we assessed total non-fasting homocysteine and methionine in plasma from 24 children with myelomeningocele. This study group (mean age 10.5 +/- 4.9 years) included 12 girls and 12 boys randomly selected from our Birth Defects Clinic. Homocysteine concentrations in our patients (4.7 +/- 1.8 mumol/L) did not differ from those of 20 randomly selected child controls (5.1 +/- 2.6 mumol/L). The mean homocysteine concentration for 36 adult controls (9.3 +/- 3.0 mumol/L) was significantly higher than the mean for either group of children (p < 0.0001). Linear regression analysis revealed negative correlation of total plasma homocysteine with serum folate (r = -0.53; p = 0.01), but not of homocysteine with either methionine or B12. Plasma methionine concentrations from our patients did not differ from adult reference values. Elevated homocysteine in some mothers of children with NTD has been attributed to defective methylation of homocysteine. These preliminary results do not indicate such a defect in the children themselves. A more comprehensive study of homocysteine, methionine and related metabolites in children with NTD and age-matched controls will be required to determine the clinical significance of these findings.