The same genes involved in predisposing people to autism appear to influence social skills in the wider population, suggesting that the autism spectrum has no clear cut-off point, scientists have discovered.

Researchers have previously shown that autism is linked not just to one or two powerful genes, but to the combined effect of many small genetic changes.

The latest findings, published in Nature Genetics, suggest that social charm, empathy and the ability to make friends is about more than just practice and upbringing, but is also affected by how many of these autism risk gene variants we possess.

Dr Elise Robinson, from Harvard University and a lead author on the paper, said: “This is the first study that specifically shows that ... factors that we have unambiguously associated with autism are also very clearly associated with social communication differences in the general population.”

Rather than viewing a person as either having or not having such a disorder, Robinson believes our social skills are better viewed as sitting on a sliding scale across the whole population.

“The primary implication is that the line at which we say people are affected or unaffected is arbitrary,” said Robinson. “There is no clear objective point either in terms of genetic risk or in terms of behavioural traits, where you can say quite simply or categorically that you’re affected or unaffected. It’s like trying to pick a point where you say someone is tall or not.”

Autism spectrum disorders are linked with a range of behaviours, including difficulties in communicating with others, maintaining friendships and empathising.



Looking at five large-scale datasets, involving more than 38,000 individuals in total, the scientists studied both rare mutations in individual genes and more complex genetic patterns across the entire genome that are known to predispose people to being diagnosed with autism.

In both cases, the team found that these genetic factors linked to autism also influenced traits relating to social communication in people who have not been diagnosed with the disorder, although the authors stress that the influence of individual genetic factors on how easy you find social situations is small.

“Across the genome, [around] 30% of the common inherited genetic influences on ASDs [austism spectrum disorders] are shared with the common inherited influences on social communication behaviour across the population,” said Robinson. “Everyone carries some degree of this kind of genetic risk.”

But, she added, these genetic factors are not alone in affecting whether people find interactions with others challenging. “We are certainly not saying that all social communication variation in the population is because of genetic risk for ASD,” said Robinson.



Commenting on the research, Carol Povey, director of the National Autistic Society Centre for Autism, said. “This research suggests that studies of the autistic population can gain from integrating studies of the general population, and so adds to the evidence that autism involves many complex and interacting factors including genetics, the environment and the development of the brain.

“While this research refers to ‘autism-related’ traits in the general population, people should not take away the message that ‘we’re all a little bit autistic’. It’s important we empathise with people on the autism spectrum, but it’s vital we understand that autism often brings particular, sometimes acute challenges for those affected.”