“When we started this study, people were expecting that only epigenetics would differ greatly between twins,” said Jan Dumanski, a professor of genetics at the University of Alabama at Birmingham and an author of the study. “But what we found are changes on the genetic level, the DNA sequence itself.”
The specific changes that Dr. Dumanski and his colleagues identified are known as copy number variations, in which a gene exists in multiple copies, or a set of coding letters in DNA is missing. Not known, however, is whether these changes in identical twins occur at the embryonic level, as the twins age or both.
“Copy number variations were discovered only a few years ago, but they are immensely important,” said Dr. Carl Bruder, another author of the study at the university. Certain copy variations have been shown in humans to confer protection against diseases like AIDS, while others are believed to contribute to autism, lupus and other conditions. By studying pairs of identical twins in which one sibling has a disease and the other does not, scientists should be able to identify more easily the genes involved in disease.
Interesting, indeed.
And, the fallout involved?
First, how much more careful do we need to be with future twin studies? How much of a grain of salt do we need to apply to past twin studies?
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