Rare genetic variations implicated in autism

Losses and duplications of whole chunks of DNA at sites across our genomes are likely to play a role in autism spectrum disorders, suggests a new international study involving Oxford University researchers and published in the journal Nature . The Oxford team now hope to carry out a pilot study to see whether tests that look for this type of genetic change can help in the diagnosis of new cases of autism. Similar tests are already in use to help diagnoses of learning disability (also called intellectual disability). 'Our research strongly suggests that this type of rare genetic variation is important and accounts for a significant portion of the genetic basis of autism,' says Professor Tony Monaco of Oxford's Wellcome Trust Centre for Human Genetics. 'By identifying the genetic causes of autism, we hope in the future to be able to improve the diagnosis and treatment of this condition which can affect children and their families so severely.' Autism spectrum disorders are known to have a predominantly genetic basis from twin and family studies, but the genetic changes responsible are varied and remain largely unknown. Single gene mutations or large rearrangements in chromosomes are responsible for a minority of cases of autism. Some rare mutations in genes are known to be risk factors for the condition, and a range of commonly occurring changes in DNA sequence have been linked to autism but only account for a small proportion of its genetic basis.