Epigenetic editing is an alternative to conventional gene editing that leaves the genome itself unharmed. Instead of cutting DNA, it tinkers with the epigenome—a set of chemical markers attached to the genome that regulate genes' activities. The approach is less intrusive than gene editing, and allows a gene's output to be modulated rather than simply switched on or off.
Epigenetic editing uses the same molecular guidance system as CRISPR: an RNA molecule that seeks out a target stretch of DNA. But the cutting enzyme (typically Cas9) is disabled, and an additional enzyme is added that attaches or removes small chemical groups—methyl groups (a carbon and three hydrogens) or acetyl groups (two carbons, three hydrogens and an oxygen)—either to the DNA itself or to the histone proteins around which DNA is wound.
Methylation of DNA stops transcription factors from binding to pertinent regions of the genetic material. Methylation and acetylation of histones affects how tightly those proteins bind to their DNA neighbour, and thus how easy it is for transcription factors to reach their targets. Manipulating these effects can fine-tune what a gene can get up to in a cell.
Since much of the genome is not involved in regulating gene activity, off-target landings by an epigenetic editor will usually be in places where they can do little harm. Conventional gene editing requires cutting the DNA molecule, and an off-target cut might disable an anticancer gene with possibly serious consequences.
Several epigenetic-editing firms were started by pioneers of conventional gene editing. Scribe Therapeutics, co-founded by Jennifer Doudna, is targeting a liver gene called PCSK9 whose silencing would reduce LDL cholesterol and thus the risk of atherosclerosis, the main cause of heart attacks and strokes.
Tune Therapeutics, based in Durham, North Carolina, and nChroma Bio of Boston are both developing epigenetic editors to disable genes of the hepatitis B virus (HBV), which infects 250m people and kills more than 1m a year. Current treatment is a daily antiviral drug that stops the virus reproducing only while it remains in the patient's system; epigenetic editing offers the possibility of a cure.
Epic Bio, founded by Stanley Qi of Stanford University, is using its GEMS platform to treat facioscapulohumeral muscular dystrophy (FSHD) by deactivating a gene that is useful in embryonic development but causes creeping paralysis when reactivated in adulthood.
A review published in January 2026 by a group at the Chinese University of Hong Kong listed a range of cancers, muscular dystrophies, rare inherited conditions such as Rett syndrome and Friedreich's ataxia, retinitis pigmentosa, chronic pain and alopecia as possible future targets.
Epigenetic editing competes with conventional gene editing and with small interfering RNAs (siRNAs), which intercept messenger molecules carrying a protein's recipe to a cell's factories. In 2022 Feng Zhang, a gene-editing pioneer, started a firm called Moonwalk Biosciences with epigenetic-editing aspirations, but the firm later shifted its attention to siRNAs. Some researchers also hope that epigenetic "factory resets" on cells using transcription factors could be used to extend human lifespan.
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