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Wednesday, 1 December, 1999, 20:08 GMT
Autism gene link
autism child A genetic test would allow easier diagnosis

Families with an autistic child have a 5% chance of having a second child with the condition, according to American researchers.

Researchers at the University of North Carolina at Chapel Hill say they may have found a genetic cause for autism.

Professor of psychiatry and newly appointed director of the university's Mental Retardation and Developmental Disabilities Research Center, Dr Joseph Piven, said that evidence pointed to the possibility of a gene on chromosome 13 causing autism.

The research - to be published in the American Journal of Medical Genetics on 15 December - involved screening the DNA of families where at least two children had autism. One family who agreed to give blood samples had three children with the condition.

'High degree of heritability'

Dr Piven said: "For a long time autism was not viewed as being a genetic disorder.

"It has a high degree of heritability, confirmed by twin studies that show a substantially higher rate in identical twins - so much so that heritability is over 90%."

He added: "The data is pretty overwhelming that autism is strongly genetic, more so than schizophrenia or diabetes.

He said that while the percentage chance of having a second child with the condition was not high, it remained "substantially higher than the rate of autism in the general population" - which is about five in 10,000 children.

The study also highlighted several other possible DNA hotspots for autism genes - notably a region on chromosome seven.

Dr Piven said: "We believe there must be more than one gene involved in autism.

As in all complex behavioural disorders, there's no clear evidence when looking at family pedigrees or family trees that suggests a single-gene may underlie this disorder."

Autism is a condition which disrupts the development of social, communication and imagination skills.

Findings welcomed

Autistic children's behaviour is often characterised by repetetive behaviour and a lack of social integration.

The findings have been welcomed by clinicians and parents' groups, who say that having a clearer idea of the causes of autism can only be a good thing.

One of the founders of the National Autistic Society, Dr Lorna Wing, who is a consultant psychiatrist whose work involves diagnosis of autism, said that a full genetic picture of the condition would aid diagnosis, and would help with family planning decisions.

She said: "A number of groups are currently working to find the genetic cause of autism.

"It seems that more than one gene is at the root of it, and it will be interesting to see if particular gene patterns are associated with certain autistic behaviour patterns.

"If families realise that there is already autism within their family, a genetic test would be able to help them decide their future family planning - and that is to the good, because in my experience, families just want to know the truth."

Chief Executive of the NAS, Paul Cann, also welcomed the research, but said that raising awareness and supporting parents and children now was equally as important.

He said: "This is very positive news. But we do have the situation now where some parents wait more than two years for a diagnosis, and that is just not acceptible."

He added that professionals and politicians could do more to understand the complexities of the condition.

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See also:
25 Nov 99 |  Wales
Mother wins battle for autistic son
18 Nov 99 |  Health
Autism link to food intolerance
03 Nov 99 |  Health
Disability: Special Report
13 Sep 99 |  Education
Special schools raising standards

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