At last the culprit in Autism is revealed

Feb 19 2007

An international team of scientists have discovered two new genetic links that may predispose children to develop autism.

In a study over a five-year period the team of researchers from 19 countries have found that autism has numerous genetic origins rather than a single or a few primary causes.

One hundred and thirty seven researchers from 50 centres worldwide constituted the Autism Genome Project.

Scouring through DNA samples from 1,168 families with two or more children with autism, has enabled them to reveal the most extensive findings to date on the genetics of the complex brain disorder.

The researchers used "gene chip" technology to detect genetic similarities and looked for tiny insertions and deletions of genetic material that could play a role in autism.

By doing this the scientists hope to be able to pinpoint the genetics of autism which could lead to better ways to diagnose the disorder and encourage the development of drugs to treat it.

The researchers suspect a gene called neurexin 1 could be the culprit.

Neurexin 1 is involved with glutamate, a brain chemical previously implicated in autism that plays a role in early brain development, along with a previously unidentified region of chromosome 11.

Autism is a spectrum of disorders apparently stemming from genetic and environmental causes.

Stephen Scherer a Geneticist at the University of Toronto who worked on the study says 90 percent of autism may have a genetic basis and they now have a better understanding of what the genetic architecture is in the autism genome.

Autistic spectrum disorders appear in early childhood, often as young as age 2 or 3, and affects four times as many boys as girls.

Such children have problems with social interaction and verbal and nonverbal communication, as well as repetitive and compulsive behaviours such as rocking and twirling or narrow and obsessive interests.

Symptoms range in severity from mild to disabling and there is no cure.

Autistic children are usually managed with drugs such as Ritalin and by behaviour modification programmes.

Some advocacy groups believe too little attention is given to environmental factors they believe may contribute to autism, such as mercury and research in the past has been focused on data from relatively few people.

The new study, using researchers from Europe and North America, shared data and expanded the number of people studied.

Co-author Dr. Peter Szatmari, director of the Offord Centre for Child Studies, says the discovery is a major breakthrough and has huge implications for autistic patients and their families.

Szatmari says not only have they found which haystack the needle is in, they now know where in the haystack that needle is located.

A good indication of the breadth the research is realised when we recognise the fact that the human genome is made up of about 30,000 genes, each containing 100,000 "letters," or chemical base-pairs called nucleotides.

Federal health experts in the United States have recently warned that autism is an urgent public health concern that is more common than previously estimated and now affects as many as one in every 150 children.

The research was funded by the nonprofit group Autism Speaks and the U.S. National Institutes of Health.

The study is published in the journal Nature Genetics.