Monday, November 17, 2008

Too Much DNA Can Cause Mutations


There's more variety to DNA than you might think: Deletions or additions of genetic material between individuals, called copy number variations (CNVs), are a common source of genetic diversity. Now, preliminary work reported here today at the American Society of Human Genetics meeting suggests that men who have more CNVs than average may be more likely to sire children with the eye cancer retinoblastoma.

All youngsters who develop retinoblastoma in both eyes inherited a defective gene that caused the disease. But in 80% of these cases, neither parent carries the mutation. Somehow it arose in the father's sperm. No one knows how this happens, but researchers have speculated that some fathers may be more susceptible to DNA damage than others.

They identified 37 CNVs they considered large--greater than 500,000 DNA bases--and in general found that the fathers had more CNVs than controls, about eight on average versus three. Twenty-one dads had no detectable CNVs at all, but Chao suspects this may be due to the technology used, which has difficulty picking up very small stretches of DNA that are duplicated or deleted.

ScienceNOW


When we first approached DNA and tried to understand it, we viewed it as lists of attributes.

Now we're seeing it's more like computer code, which means something in the wrong place is more destructive than the "wrong thing" existing.

When we understand it as well as we understand, say, x86 assembly, we will start to perceive how locations correspond to developmental cycles and as a result, when organs develop in the fetus and as a result of what, WHICH piece of the human each DNA area addresses.

Right now, we're mostly trying to correlate areas with effects, which provides statistical "accuracy" for some things but will not explain all; that awaits our understanding DNA more fully.

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