Thursday, November 23, 2006

Major breakthrough in human genome announced.

Today a major advance in human genetics is published.  They have finally figured out something that has been puzzling all of us for a long time, why are people so different if 99.9% of their DNA is identical?  Because it isn't identical after all!  Shazam!

What have scientists discovered today?

They have found that each of us is more different genetically than we previously believed. Instead of being 99.9 per cent identical, it may turn out to be more like 99 per cent identical - enough of a difference to explain many variations in human traits. Instead of having just two copies of every gene - one from each parent - we have some genes that are multiplied several times. Furthermore these "multiple copy numbers" differ from one person to another, which could explain human physical and even mental variation.

Why does this matter?

One practical benefit is that it could lead to a new understanding of some of the most difficult, incurable diseases. Although it adds an extra layer of complexity to our understanding of the human genome, the discovery could lead eventually to new insights and medical treatments of conditions ranging from childhood disorders to senile dementia. Scientists are predicting for instance that the knowledge could lead to new diagnostic tests for such diseases as cancer.

How was this discovery made?

Scientists have developed sophisticated methods of analysing large segments of DNA over recent years. "In some ways the methods we have used are 'molecular microscopes', which have transformed the techniques used since the foundation of clinical genetics where researchers used microscopes to look for visible deletions and rearrangements in chromosomes," explained Nigel Carter of the Sanger Institute in Cambridge.

What genes are copied many times and why?

There are just under 30,000 genes in the human genome, which consists of about 3 billion "letters" of the DNA code. The scientists found that more than 10 per cent of these genes appear to be multiplied in the 270 people who took part in the study. They do not know why some genes are copied and some are not. One gene, called CCL3L1, which is copied many times in people of African descent, appears to confer resistance to HIV. Another gene involved in making a blood protein is copied many times in people from south-east Asia and seems to help against malaria. Other research has shown that variation in the number of copies of some genes is involved in Alzheimer's and Parkinson's disease.

Are there any other practical applications?

The scientists looked at people from three broad racial groups - African, Asian and European. Although there was an underlying similarity in terms of how common it was for genes to be copied, there were enough racial differences to assign every person bar one to their correct ethnic origin. This might help forensic scientists wishing to know more about the race of a suspect.

Who made the discovery and where can we read more about it?

Scientists from 13 research centres were involved, including Britain's Sanger Institute in Cambridge, which also took a lead role in deciphering the human genome. The research is published in Nature, Nature Genetics and Genome Research.

I predict a lot more of this kind of discovery.  The genome cannot possibly be as simple as we think.  I mean, there's bacteria with more raw DNA than what we have, why aren't they more complicated?  Therefore coding must be much more complex than a simple one dimensional "tape" of DNA.

For one thing, we have more brain cells than DNA base pairs.  What decides where all those cells go?  Since they seem to end up in the right place almost every time, something must be doing that job eh?  So that mechanism must be coded fore somehow.

Then there's protein folding to consider.  If protein A folds one way it does one thing, if it folds another way it does something completely different.  Same chain of components, different fold.  There's a lot of data required to "remember" all those folds, and its in the DNA somehow.

Therefore I think we can expect lots more emergent properties to be discovered over the next few years, which will probably change not only biology but computer science as well.  This is very exiting stuff!

The Phantom

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