Identical twins not as identical as believed

February 15, 2008

Contrary to our previous beliefs, identical twins are not genetically identical. This surprising finding is presented by American, Swedish, and Dutch scientists in a study being published today in the prestigious journal American Journal of Human Genetics. The finding may be of great significance for research on hereditary diseases and for the development of new diagnostic methods.

How can it be that one identical twin might develop Parkinson’s disease, for instance, but not the other? Until now, the reasons have been sought in environmental factors. The current study complicates the picture.

“Even though the genome is virtually identical in identical twins, our results show that there in fact are tiny differences and that they are relatively common. This could have a major impact on our understanding of genetically determined disorders,” says Jan Dumanksi, who co-directed the international study with his colleague Carl Bruder.

“By uncovering these small genetic differences in identical twins where one of them is sick, we have a way of tying specific genetic changes to the genesis of common diseases,” says Carl Bruder.

These researchers studied 19 pairs of identical twins and found that they indeed had the same DNA but nevertheless evinced differences in the number of copies of individual DNA segments. A segment might be missing, or more copies might exist in one twin. This could explain how one identical twin can be afflicted with a disorder while the other twin remains fully healthy, according to the scientists.

Source: Uppsala University

Explore further: Twin research reveals which facial features are most controlled by genetics

Related Stories

Is transgender identity inherited?

March 3, 2017

The recent return of the "which bathroom?" issue regarding transgender individuals' use of public restrooms has made me think about how I've handled sex and gender in my human genetics textbook. Over the editions, the two ...

The life-saving treatment that's being thrown in the trash

March 28, 2017

A few hours before beginning chemotherapy, a man named Chris faces his cellphone camera with a mischievous smile and describes a perfectly absurd milestone at 1.37pm on a Wednesday. "There is no more beautiful moment in a ...

Recommended for you

New insights on triggering muscle formation

April 26, 2017

Researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) have identified a previously unrecognized step in stem cell-mediated muscle regeneration. The study, published in Genes and Development, provides new ...

Risk of obesity influenced by changes in our genes

April 25, 2017

These changes, known as epigenetic modifications, control the activity of our genes without changing the actual DNA sequence. One of the main epigenetic modifications is DNA methylation, which plays a key role in embryonic ...

3 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

googleplex
3 / 5 (3) Feb 15, 2008
Ok the infamous Physorg bogus headline strikes again.
It should say "indentical twins used to find disease genotypes".
It is implicit in what the article says that 'theoretically ideal' identical twins have genetically identical DNA. However in practice mutations can occur to one twin that cause small differences. In some instances this can be used to identify disease genotypes.
gopher65
1 / 5 (1) Feb 16, 2008
Indeed googleplex. My thoughts exactly.
superhuman
not rated yet Feb 25, 2008
No, the title is correct. The article says that there are more differences between homozygous twins then there should be according to our current knowledge.
And "indentical twins used to find disease genotypes" is no news its been like that for decades.

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.