Autism spectrum disorders (ASD) - a class of syndromes grouped by shared impairments in social communication - have so far eluded researchers' attempts at genetic characterisation, due in part to ASD's clinical diversity. Although family studies suggest a strong genetic dimension to ASD, prior studies only found genetic factors in 20 percent of patients, at most.
But early results (32 patients were included together with their families) from what researchers claim is the world's first large-scale autism study to sequence entire genomes, rather than just the regions that code for proteins, suggest that estimate is conservative.
Dr Steve Scherer, director of the Centre for Applied Genomics at The Hospital for Sick Children in Canada, told The Canadian Press: 'What we're saying is, based on this pilot study, if you take 100 new diagnoses of autism and we sequence in their genomes, in 50 percent [...] we would find a genetic variant that either explains their autism or some of the associated medical complications that come along with that'.
But Dr Scherer adds: 'We can't say we found in those individuals the cause of autism'.
Instead, this technique discovered both inherited and spontaneous mutations associated with ASD symptoms by comparing the genomes of ASD individuals to their parents'. To a burgeoning collection of over 100 known ASD risk genes, the researchers unearthed four new genes that appear related to ASD, and eight candidate genes. They corroborated a further ten genes put forward as candidates by other groups.
ASD is thought to arise biologically from variable combinations from a set of hundreds of risk genes, many of which most people with autism will not carry.
The Hospital for Sick Children, BGI-Shenzhen in China and Duke University in the USA ran the study as the pilot of an initiative championed by ASD charity and advocacy group Autism Speaks to sequence the genomes of 10,000 individuals with, or related to someone with, ASD.
The researchers hope to use whole genome sequencing to uncover more genes and, in doing so, clarify the causes of ASD.Dr Robert Ring, Autism Speaks' chief science officer and study co-author, commented: 'From diagnosis to treatment to prevention, whole genome sequencing efforts like these hold the potential to fundamentally transform the future of medical care for people with autism'.