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: Bangladeshi twins born joined at skull to undergo surgery

Related Stories

Bangladeshi twins born joined at skull to undergo surgery

July 26, 2017
Bangladeshi twins born conjoined at the skull will undergo a difficult and potentially dangerous operation to separate them, surgeons said Wednesday as they appealed for help from global medical experts.

Bangladesh separates conjoined twins in rare surgery

August 2, 2017
Ten-month-old Bangladeshi siamese twins were recovering in hospital Wednesday after what surgeons hailed as the country's "groundbreaking" first successful separation operation on conjoined siblings.

Experiment finds evidence for the Majorana fermion, a particle that's its own antiparticle

July 20, 2017
In 1928, physicist Paul Dirac made the stunning prediction that every fundamental particle in the universe has an antiparticle – its identical twin but with opposite charge. When particle and antiparticle met they would ...

Why is one twin smaller than the other? Answer could lie in the placenta

June 16, 2017
When a baby is born small, it's often attributed to genetic factors or maternal risk factors like poor nutrition or smoking. But a twin study led by researchers at Boston Children's Hospital now find that slower transport ...

How children look at mom's face is influenced by genetic factors and altered in autism

July 12, 2017
New research has uncovered compelling evidence that genetics plays a major role in how children look at the world and whether they have a preference for gazing at people's eyes and faces or at objects.

Immune system cell clones created before birth may last for decades

July 6, 2017
Key immune system cells produced before birth may survive well into adulthood, according to new research published in PLOS Computational Biology.

Recommended for you

Gene variant activity is surprisingly variable between tissues

August 21, 2017
Every gene in almost every cell of the body is present in two variants called alleles—one from the mother, the other one from the father. In most cases, both alleles are active and transcribed by the cells into RNA. However, ...

Genome analysis with near-complete privacy possible, say researchers

August 17, 2017
It is now possible to scour complete human genomes for the presence of disease-associated genes without revealing any genetic information not directly associated with the inquiry, say Stanford University researchers.

Science Says: DNA test results may not change health habits

August 17, 2017
If you learned your DNA made you more susceptible to getting a disease, wouldn't you work to stay healthy?

Genetic variants found to play key role in human immune system

August 16, 2017
It is widely recognized that people respond differently to infections. This can partially be explained by genetics, shows a new study published today in Nature Communications by an international collaboration of researchers ...

Phenotype varies for presumed pathogenic variants in KCNB1

August 16, 2017
(HealthDay)—De novo KCNB1 missense and loss-of-function variants are associated with neurodevelopmental disorders, with or without seizures, according to a study published online Aug. 14 in JAMA Neurology.

Active non-coding DNA might help pinpoint genetic risk for psychiatric disorders

August 16, 2017
Northwestern Medicine scientists have demonstrated a new method of analyzing non-coding regions of DNA in neurons, which may help to pinpoint which genetic variants are most important to the development of schizophrenia and ...

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.