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Monday, 1 April, 2002, 14:10 GMT 15:10 UK
Autism gene hunt narrows
Scientists are probing DNA for clues to autism
Scientists are closing in on the handful of genes linked to autism - by eliminating those not connected with the condition.

They hope that within two years, their efforts will identify most of the genetic "faults" which contribute to its development.

Current thinking suggests there are at least four, and perhaps as many as 10 genes which play a role in autism.

Autism is an umbrella term for a large number of similar "developmental disorders".

All clear for genes

These normally strike in the first few years of life, and severely curtail social and communication skills.

We hope that in about two years, we can find these genes

Professor Anthony Monaco, Oxford University
Autistic children, in general, find it much harder to relate to the outside world.

Four studies into the genetic roots of autism have been published on Monday in the journal Molecular Psychiatry.

Three of them look into genes previously suspected of playing a part - but have given them the all-clear.

Only one adds to positive evidence that a particular gene is involved.

This reflects the pattern of research across the world - studies pointing conclusively to one or more genes have proved elusive.

Scientists are fairly certain that they have found a few tiny regions among the millions of genes on human DNA which hold the key.

However, each of these carries hundreds of individual genes, and their work now is to painstakingly pick out and test these one by one.

Professor Anthony Monaco, Director of The Wellcome Trust Centre for Human Genetics at the University of Oxford, co-authored one research paper published on Monday.

This ruled out four potential autism genes located on one particular tiny region of the cell's DNA.

Hard work

He said: "It's pretty labour intensive work, and in this instance, hasn't come up with anything particularly exciting.

"Computer models suggest that there are somewhere between three and 10 genes involved in the development of autism.

"We are encouraged by the fact that we have narrowed the search down to two or three regions.

"We hope that in about two years, we can find these genes. If we don't do it, someone else will by then."

However, finding the genes, while important, is only the first step towards finding ways to help autistic children, and their parents.

It is likely that other things have a bearing on the development of the condition - as yet unidentified "environmental" factors which may help trigger the decline, or how severe the autism is in any child.

Professor Monaco said: "We know that you can have identical twins - who have exactly the same genes - and one of them will get severe autism, and the other one will get a milder version.

"We don't yet know why that is."

However, once the genes have been identified, scientists can continue to unravel these mysterious connections, devise screening tests for children, and perhaps even treatments which could prevent autism, or even reverse it in affected children.

See also:

07 Oct 99 | Health
Tuning in to genius
30 Jun 99 | Health
Immune link to autism
04 May 99 | Health
Autistic children 'let down'
12 Feb 01 | A-B
Asperger's syndrome
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