https://www.annualreviews.org/doi/abs/10.1146/annurev-bioeng-071516-044720
see also
https://genomebiology.biomedcentral.com/articles/10.1186/gb4179
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6205890/
https://the-gist.org/2016/09/epigenetic-engineering-the-next-generation-of-gene-editing/