Monday, 18 Dec 2006 15:19
Scientists have discovered the genetic problem that is likely to cause autism in some individuals.
Writing in the journal Nature Genetics, researchers from a number of European institutes argue that the discovery could provide new insights into the biological basis for the condition.
Autism spectrum disorders (ASD) currently affect six out of every 1,000 children and cause a range of social and communicative disorders.
Scientists estimate that between three and six per cent of ASD are caused by chromosomal rearrangements; chromosome 22 has a small region which is frequently affected in people with conditions associated with autism.
By looking at one of the genes a€" Shank3 a€" on this chromosome in 200 people with ASD, "unambiguous alterations" were found in three families.
Shank3 interacts with proteins known as neuroligins which play a role in creating neuronal signals.
In one of the families an individual had significant deletion of Shank3, while two brothers in the second family had a smaller amount of deletion; an unaffected brother and parents of the boys were found to have no mutation on the gene.
In the third family, a girl with an ASD had a deletion of Shank3 while her brother, who has Asperger's Syndrome, a mild form of autism, had an additional copy of the gene.
Explaining the significance of their findings, the researchers write: "These mutations concern only a small number of individuals, but they shed light on one gene dosage a€" sensitive synaptic pathway that is involved in autism spectrum disorders."
They conclude that as a result of their findings, future research into the biological basis of ASD should focus increased attention on neuroligin function.
