In the last decade, evidence has been accumulating on the role of epigenetic modifications of DNA in complex common disease. In particular, epigenetic modifications provide a link between environmental risk factors and disease. While it is well known that genetic background is a crucial component in the probability of methylation at an epigenomic locus, the extent of this influence has not been evaluated in humans beyond the use of twin pairs. However, twin pairs potentially do not provide an accurate representation of the population given their environmental sharing and the link between the environment and DNA methylation.
In order to investigate the genetic control of DNA methylation, a total of 600 individuals including twin pairs, their singleton siblings and parents have been measured for DNA methylation levels in whole blood using Illumina Infinium HumanMethylation450 BeadChip arrays. The correlation in DNA methylation levels is investigated using the different types of relationship pairs in the dataset, providing a more complete picture of the inheritance of DNA methylation. The results from genome-wide association studies to detect genetic variants underlying variability in DNA methylation will be presented.