A new study has found that all people, including those who have not been diagnosed with a condition on the spectrum, show symptoms of autism in them. Researchers from the University of Bristol, the Broad Institute of Harvard and MIT, and Massachusetts General Hospital investigated the genetic relationship between autistic spectrum disorders (ASD) and ASD-related traits in people not considered to have ASD.
They found that genetic risk for ASD exists in all people, but we display symptoms associated with the condition to “various degrees.” According to the study, autism spectrum disorders (ASD) are a class of neuro-developmental conditions affecting about one in 100 children. The disorders are characterised by social interaction difficulties and communication and language impairments, as well as stereotyped and repetitive behaviour.
These core symptoms are central to the definition of an ASD diagnosis but also occur, “to varying degrees”, in unaffected individuals and form an “underlying behavioural continuum.” The researchers noted that most ASD risk is polygenic, meaning it stems from the combined small effects of thousands of genetic differences, distributed across the genome (a set of genes present in a cell).
But in some cases, ASD risk is also linked to rare genetic variants or mutations, which are usually de novo (not inherited).
“Once we had measurable genetic signals in hand – both polygenic risk and specific de novo mutations known to contribute to ASD – we were able to make an incontrovertible case that the genetic risk contributing to autism is genetic risk that exists in all of us, and influences our behaviour and social communication,” senior study author Dr Mark Daly said.
