31 May 2011
ByAppeared in BioNews 609
Gene activity in two brain regions is different in people with autism, scientists say. A US study found activity patterns were similar in the frontal and temporal lobes of people with autism, despite the lobes having different functions. This may be due to defective brain development and could improve our understanding of the genetic component of autism, the study authors say.
Senior author Professor Daniel Geschwind from the University of California, Los Angeles, told the BBC: 'If you randomly pick 20 people with autism, the cause of each person's disease will be unique. Yet when we examined how genes and proteins interact in autistic people's brains, we saw well-defined shared patterns. This common thread could hold the key to pinpointing the disorder's origins'.
Many previous studies have looked for differences between the DNA of people with and without autism. Professor Geschwind and his colleagues instead looked at mRNA levels in brain tissue samples from 19 people with autism and 17 without the condition. Studying mRNA let them look for abnormalities in gene expression.
The study found mRNA levels for over 200 genes linked to brain cell communication were lower in the brains of people with autism. Another 200 or so genes linked to inflammation and immune response were more active in the brains of people with autism than they should be. Several of these genes – and the frontal and temporal lobe - were previously linked to autism, according to TIME magazine.
More than two-thirds of the autism patients shared the same abnormal gene activity patterns. This suggests the condition has a characteristic 'brain signature', The Scientist reports.
Dr Karoly Mirnics, a neuroscientist from Vanderbilt University not involved in the research, said in Nature: 'The paper implies that the different brain regions in autism are not specialised as they should be. It very well might be the result of impaired development'. The study was published in Nature.
More than 500,000 people have so-called autism spectrum disorders in the UK. Both environmental and genetic factors may influence development of the condition.