Twin study reveals epigenetic alterations of psychiatric disorders

September 21, 2011

In the first study to systematically investigate genome-wide epigenetic differences in a large number of psychosis discordant twin-pairs, research at the Institute of Psychiatry (IoP) at King's College London provides further evidence that epigenetic processes play an important role in neuropsychiatric disease. Published in Human Molecular Genetics, the findings may offer potential new avenues for treatment.

Previous quantitative of and reveal strong inherited components to both. However, although for schizophrenia and bipolar disorder is estimated at 70%, disease concordance between twin-pairs is far from 100%, indicating that non-genetic factors play an important role in the onset of the diseases.

Dr. Jonathan Mill, lead author of the study at the IoP says, 'We studied a group of 22 identical twin-pairs, so 44 individuals in all, one of the largest twin studies performed for any complex disease to date. In each twin-pair, one had either schizophrenia or bipolar disorder. Because we know that twins are genetically identical, we can rule out any of illness in the affected twin – the aim of our study was to investigate epigenetic variations associated with these disorders.'

Epigenetic mechanisms are linked to heritable, but reversible, changes in gene expression without a change in the underlying DNA sequence. This happens principally through alterations in DNA methylation and chromatin structure. Epigenetic changes in the brain have previously been associated with a range of biological and cognitive processes, including neurogenesis, drug addiction and neurodegeneration. It has also been suggested that epigenetic changes in the brain may be involved in a spectrum of psychiatric disorders including psychosis.

The researchers looked at differences in DNA methylation across the genome using DNA taken from both the affected and unaffected twins in each monozygotic twin-pair. The findings were then compared to DNA samples taken from post-mortem brain material from psychosis patients and controls.

Whilst the researchers found no alterations in overall DNA methylation content between affected and unaffected twins, there were considerable disease-associated differences between twins at specific sites across the genome. The findings confirmed previously known sites implicated in psychiatric disorders as well as revealing previously unknown ones.

Dr. Mill adds, 'Our findings suggest that it is not only genetic variations that are important. The epigenetic differences we see may tell us more about the causes or schizophrenia and bipolar disorder, as some alterations were specific to either disease. Importantly, epigenetic processes are potentially reversible meaning that our research could open up new avenues for the development of novel therapeutic drugs.'

More information: Dempster, E. et al. 'Disease-associated epigenetic changes in monozygotic twins discordant for schizophrenia and bipolar disorder', Human Molecular Genetics doi: 10.1093/hmg/ddr416

Related Stories

Recommended for you

New target could eliminate lurking cancer stem cells

November 27, 2015

Scientists from Trinity College Dublin have identified a novel target that could help to identify 'cancer stem cells' while they are in their inactive state. The scientists could then jolt these cells into action so that ...

New class of RNA tumor suppressors identified

November 23, 2015

A pair of RNA molecules originally thought to be no more than cellular housekeepers are deleted in over a quarter of common human cancers, according to researchers at the Stanford University School of Medicine. Breast cancer ...

Batten disease may benefit from gene therapy

November 11, 2015

In a study of dogs, scientists showed that a new way to deliver replacement genes may be effective at slowing the development of childhood Batten disease, a rare and fatal neurological disorder. The key may be to inject viruses ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.