Advancing Epigenetics Towards Systems Biology

Twin Profiles


Jason (left) and Gavin (right)
aged 29


Jason (left) and Gavin (right)
aged 7 with Mum and Nan

Brona McVittie reports :: June 2006

"At times in their lives they have definitely striven to be perceived as a unit and at other times seem to want people to acknowledge their differences and respect them as individuals," says Jimmy of his friends Gavin and Jason. Gavin and Jason are identical twins. One is a literally a clone of the other. Their similarities cannot be disputed, but when I first met them, I found them to be quite different people. Had I met them a few years ago, I doubt I would have been able to tell them apart.

Monozygotic twins arise with an incidence of 1 in every 250 births worldwide. For reasons yet unknown, a fertilized egg cell can clone itself and give rise to separate embryos. Each will begin and end life with the same genetic make-up, but as they grow and develop they will experience differences in their environment, some of which might alter their appearance and behaviour.

Gavin and Jason have exactly the same DNA. If one committed a crime and unwittingly left samples for forensic analysis, it would be impossible to determine the baddie from DNA fingerprint analysis. However, closer inspection of their molecules may reveal significant differences. Although the lads share the same genes, recent evidence suggests that some genes might be active in one twin and not the other. They might be identical genetically but not epigenetically.

Such differences are discernable at the molecular level in the way that their chromosomes are arranged within the nucleus of each cell. Twisted around tiny protein balls, the same DNA can have different consequences for a cell. Both balls and string assume complex 3D structures depending on their biochemical flavour. A variety of small molecules can affect the nuclear infrastructure by adhering to both DNA and associated histone proteins. Such flavours are influenced by the environment, most notably our diet.

Biochemical fine-tuning of the genome determines which genes get switched on, so twins are not necessarily destined to share the same fate. Recent research on monozygotic twins has revealed that their DNA is marked in different ways by a tiny molecule called methyl. So it's not really true to say that they are identical. What's more, these differences were much more pronounced in older than younger twins.

This is new fodder for the age-old debate over how much the environment influences our fate relative to our genes. Although the similarities between identical twins are more striking than the differences, their inequalities could offer new avenues for disease research. For example, although Gavin and Jason are both at risk of type II diabetes, Jason was recently admitted to hospital with serious pancreatic problems and had to inject himself with insulin for some time afterwards. The doctors were unable to make a specific diagnosis. Had they been equipped with better diagnostic tools, such as are offered by new advances in epigenetic research, they might have been able to profile the twins to see whether DNA methylation patterns were involved.

Many diseases have a known genetic component, but may be modified by epigenetics. Epigenetic features like DNA methylation are much more viable targets for treatment because it's much easier to change the way DNA is methylated than to change the underlying DNA sequence.

Mon, May 29th 2017- Wed, May 31st 2017

After last year's successful kick-off meeting, the EpiGeneSwiss meeting will take place again in Weggis, Switzerland. This year we have added one day in addition to accommodate more topics and more t...

Mon, Jun 19th 2017- Wed, Jun 21st 2017

The focus of the 2017 IMB Conference is on “Gene Regulation by the Numbers: Quantitative Approaches to Study Transcription”. The conference will explore the latest findings and technological developme...

Tue, Jul 11th 2017- Thu, Jul 13th 2017

The MRC Integrative Epidemiology Unit at the University of Bristol invites all professionals interested in aetiological epidemiology and Mendelian randomization to attend our conference on the subject...

Wed, Aug 30th 2017- Fri, Sep 1st 2017

The nucleosome is the fundamental building block of chromatin organisation and genome function. The 20th anniversary of the high resolution nucleosome structure marks a milestone for bringing together...


EpiGeneSys Final
Meeting in Paris

Thur. 11 February 2016 - Sat. 13 February 2016

More than 280 scientists attended the fifth Annual Meeting of EpiGeneSys. The conference kicked off with a talk by coordinator Geneviève Almouzni, Director of the Research Center at the Institut Curie, highlighting the achievements of the network over more than five years...

Maison des océans - Paris Read more


The Non-Coding Genome ...

December 3-4 th, 2015

The last training workshop of the EpiGeneSys network

Hotel Mediterraneo - Rome, Italy Read more

Paris / TriRhena Chromatin Club

July 9th, 2015

...exciting talks and network with members of the Chromatin community!

... An EpiGeneSys TAB workshop

June 11st-12nd , 2015

... learn about current approaches to single cell epigenetics and to meet up and network with...

Montpellier, FranceRead more

Latest publications


The impact of rare and low-frequency genetic variants in common disease.

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Stable Polycomb-dependent transgenerational inheritance of chromatin states in Drosophila.

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Stable Polycomb-dependent transgenerational inheritance of chromatin states in Drosophila.

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