29 June 2009
ByAppeared in BioNews 514
Scientists at the University of Aberdeen, Scotland, have discovered a gene which may mediate the cognitive effects of autism. After detecting a chromosomal rearrangement in one severely autistic boy, the team, headed by Dr Zosia Miedzybrodzka, was inspired to look for similar genetic faults in other autistic families. Thier findings are published in the latest issue of Journal of Medical Genetics.
Dr Miedzybrodzka and her colleagues found that the boy had a chromosomal rearrangement which disrupted the EIF4E gene, known to play a key role in memory and learning. Dr Miedzybrodzka said: 'our discovery is particularly important because several genetic pathways, already known to cause autism, are channelled through this gene.'
The team went on to survey a further 120 autism families and found two families where a pair of siblings with autism, as well as one of thier parents, showed abnormalities in EIF4E. The team also screened a control group of 1020 individuals with no autistic symptoms for the same gene mutations.
It is hoped that a better understanding of the causes of autism will lead to improved strategies for managing and treating the condition. 'Our finding paves the way for development of new treatments for this common and upsetting condition,' Dr Miedzybrodzka told the BBC.
Earlier this year researchers from the Children's Hospital in Philadelphia discovered six variations that increase the risk of autism, all of which are located on chromosome 5 between two genes, CDH10 and CDH9. These genes code for proteins called cell adhesion molecules, which are important in making connections and communication between brain cells. One of the variations identified was shown to occur in more than 65 per cent of cases, although the scientists estimated it only plays a major role in about 15 per cent, and that other, unknown factors are more important in the remainder.
Another study, published at the same time in the journal Molecular Psychiatry and led by Professor Tony Monaco from the Wellcome Trust Centre for Human Genetics in Oxford, UK, also identified a link between a gene important for growth and development of brain cells and autism.
It has long been known that autism can sometimes run in families, suggesting a genetic component, however research shows that other environmental factors play a major part too. There are now more than 133 genes linked to autism and further research will be needed to understand exactly how these interact with each other and the environment to increase an individual's risk of developing autism.
Autism - along with several related conditions together known as autistic spectrum disorders - is a lifelong developmental disability that typically appears during the first three years of life. The disorder affects social and language skills, and the way in which a child relates to people, objects and events. Although autism often runs in families, many children are born to parents with no history of the condition.