A longitudinal study of epigenetic variation in twins

Epigenetics. 2010 Aug 16;5(6):516-26. doi: 10.4161/epi.5.6.12226. Epub 2010 Aug 16.


DNA methylation is a key epigenetic mechanism involved in the developmental regulation of gene expression. Alterations in DNA methylation are established contributors to inter-individual phenotypic variation and have been associated with disease susceptibility. The degree to which changes in loci-specific DNA methylation are under the influence of heritable and environmental factors is largely unknown. In this study, we quantitatively measured DNA methylation across the promoter regions of the dopamine receptor 4 gene (DRD4), the serotonin transporter gene (SLC6A4/SERT) and the X-linked monoamine oxidase A gene (MAOA) using DNA sampled at both ages 5 and 10 years in 46 MZ twin-pairs and 45 DZ twin-pairs (total n=182). Our data suggest that DNA methylation differences are apparent already in early childhood, even between genetically identical individuals, and that individual differences in methylation are not stable over time. Our longitudinal-developmental study suggests that environmental influences are important factors accounting for interindividual DNA methylation differences, and that these influences differ across the genome. The observation of dynamic changes in DNA methylation over time highlights the importance of longitudinal research designs for epigenetic research.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child
  • Child, Preschool
  • DNA Methylation
  • Epigenesis, Genetic / physiology*
  • Female
  • Genetic Variation / physiology*
  • Genomic Instability
  • Humans
  • Inheritance Patterns / genetics
  • Longitudinal Studies
  • Male
  • Monoamine Oxidase / genetics
  • Receptors, Dopamine D4 / genetics
  • Serotonin Plasma Membrane Transport Proteins / genetics*
  • Twins / genetics*


  • DRD4 protein, human
  • SLC6A4 protein, human
  • Serotonin Plasma Membrane Transport Proteins
  • Receptors, Dopamine D4
  • Monoamine Oxidase