Considering the potential role of sulfur amino acid metabolism in DNA methylation and fetal programming, we further analyzed the mRNA expression of enzymes related to sulfur amino acid metabolism, this result indicated that methionine synthase (MS) was 6.5-fold increase (P value < 0.01) in the jejunum tissue of IUGR relative to normal littermates (S3 Table). The gene discussed is MTR; the disease is fetal growth restriction.