Major genetic clue to autism uncovered

An international research effort has found genes that may significantly increase the risk for developing autism.

Hot on the heals of the disclosure by medical authorities that autism rates are increasing even more rapidly than previously thought, a major breakthrough in the understanding of the genetics of the condition was announced yesterday.

The research that led to the discovery involved a major international collaboration of more than 130 researchers from 50 institutions in eight countries. The effort was coordinated by the Autism Genome Project, a large-scale, collaborative genetics research project initiated by the National Alliance for Autism Research and the National Institutes of Health, which is aimed at sifting through the human genome in search of autism-susceptibility genes.

The international team of researchers carried out scans of DNA from 8,000 people in 1,600 families. By studying families that had multiple cases of autism they were able to look for genetic markers that were common to them. From all that data, scientists uncovered two new gene mutations possibly linked to an increased susceptibility to autism. This huge research effort took nearly 5 years to complete, having started in 2002, and required a large amount of funding.

Governments and institutions are becoming more aware of the importance of funding more autism research efforts such as this in light of the fact that the condition now effects as many as 1 child in 150. There are no signs that the rate of increase is set to slow.

It is hoped that the knowledge acquired through this latest research will lead to more effective medications and therapies, as well as accurate diagnostic tests with which to screen children so that early preventative measures can be implemented before autism develops.

After the researchers gathered DNA samples from the autistic volunteers they used a technique known as linkage, which involved using microchips to compare 10,000 DNA markers to identify shared chromosome regions amongst those with autism. The scientists found a common gene on chromosome 11. Another susceptibility gene found was a gene called Neurexin 1, which believed to be important for allowing different parts of the brain to communicate with each other efficiently.

The research team say the next step will be to test the Neurexin 1 gene markers in another sample of people and see if it replicates. If it did, this would provide an important target for future treatment and screening test development.

The researchers also found that some autism cases were linked to gene mutations or missing chromosomes. Stephen Scherer, a researcher at the Hospital for Sick Children, Toronto, Canada, is quoted as saying of the research, "We've identified in about five to 10 (autism) cases that there are changes in the chromosomes themselves," and he went on to describe the study's findings as a "giant step" for autism research.

It's clear that these findings represent another major piece in the autism puzzle. The researchers say that autism clearly has a major genetic component but that this does not rule out the involvement of environmental triggers. Indeed, many experts now believe that autism (and many other chronic illnesses for that matter) results from an interplay of genetic susceptibilities and environmental triggers. A few weeks ago I reported on research carried out by Dr. Bartzokis, who believes that genetic differences that lead to differences in the thickness of myelin between the sexes accounts for the fact that many more boys than girls develop autism. Myelin is the material that protects neurons from damage by various substances including environmental toxins.