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I thought I'd pass this along to folks.  Twins may not be as similar  
as we all thought:

>
>
>
> Feb 14,2008
> Identical twins not as identical as believed
>
> 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
>
>

Charles Carlson
Director of Life Sciences
exploratorium
3601 Lyon St.
San Francisco, CA 94123
[log in to unmask]
Tel:   415-561-0319
Fax:  415-561-0370



Charles Carlson
Director of Life Sciences
exploratorium
3601 Lyon St.
San Francisco, CA 94123
[log in to unmask]
Tel:   415-561-0319
Fax:  415-561-0370



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