Cytosine residues in DNA that can be methylated (i.e. CpG sites) are likely to be in the same methylation state if they are geographically (proximally) close together.
I can only find one paper that states this empirically (1), that 90% of CpG sites within 50bp of one another are in the same methylation state - see below graph.
However this study is quite dated now (in the fields of epigenetics at least), and is very general.
I would like to know whether CpG's in different regions of the genome are more/less likely to be correlated than in other regions (say, exons vs. promoter regions). It would also be interesting to know whether the correlations change with age, and whether this is related to any disease processes?
Thanks for the input.
- Eckhardt, et al, 2006. Nature Genetics. doi: 2010.1038/ng1909