01 May,2009 04:54 PM IST | | PTI
Variations in a gene thought to be involved in the growth and development of nerve cells in the brain could be associated with susceptibility to autism, a new international study suggests.
The research is led by Oxford University researchers and has been published in the journal Molecular Psychiatry. Related papers by US researchers, which are published in the journal Nature at the same time, have identified other candidate genes associated with increased risk of autism spectrum disorders.
These genes are also involved in the formation of connections between nerve cells in the brain. Together, these three studies begin to build a picture of the complex genetic origins of autism spectrum disorders, the University of Oxford said. It appears that there may be many common gene variants that each increase autism susceptibility by only small amounts, but that many of them play a role in processes to do with making neural connections in the brain.
"Most of the genes that have been identified in these studies are involved in the connections between neurons called synapses," says Professor Tony Monaco of the Wellcome Trust Centre for Human Genetics at the University of Oxford. "This does seem to fit with what we know from brain scans that people with autism may show different or reduced connectivity between different parts of the brain." he added.
The Oxford University team, along with colleagues from the International Molecular Genetic Study of Autism Consortium at universities in Europe and the US, did a fine scan of regions on chromosome 2 and chromosome 7 that had been previously connected with increased risk of these conditions. The researchers found that DOCK4 on chromosome 7 may increase susceptibility to autism spectrum disorders.
The DOCK4 gene is thought to be involved in the growth of dendrites the long arms that extend from nerve cells to connect them and pass electrical signals to other neurons in the brain. "This is a new finding DOCK4 had not previously been associated with autism before," says Alistair Pagnamenta of Oxford University, one of the lead authors of the study. Autism spectrum disorders are a group of developmental disorders that emerge in early childhood which have a large, but complex genetic component.
The disorders are characterised by difficulties in social interaction, communication, and understanding other people's emotions and behaviour.
