Engineers, scientists may carry autism gene

OPINION:Question: "How would you recognise an extrovert mathematician?" Answer: "He's the mathematician who looks at your shoes when he's talking to you."

Such odd behaviour is not uncommon among academic researchers who specialise in technical analysis: mathematicians, engineers, scientists, IT specialists, and so on.

Of course, a degree of introversion falls far short of autism, but Simon Baron-Cohen, director of the autism research centre at Cambridge University, presents a fascinating hypothesis that children of scientists, engineers or mathematicians tend to inherit genes that predispose them to autism together with the genes that confer their specialist intellectual talents (Scientific American, November 2012).

Autism is a neural development disorder characterised by impaired social interaction and communication and by restricted and repetitive behaviours. Diagnostic criteria require that symptoms be present before the child is three years old. Autism is one of several conditions classified as “autism spectrum disorders” (ASD), including Asperger’s syndrome, a “high performance” variety of autism with normal language development.

One to two children in 1,000 have autism and about 11 per 1,000 children have an ASD. Autism is more common than previously thought but it is unclear whether this reflects an increasing rate or an increased ability to diagnose the illness.

Many parents worry that vaccination may cause autism but the expert medical opinion is that no vaccine or vaccine component explains the numbers of children diagnosed with autism, and that the benefits of vaccination greatly outweigh the risks (according to data from the US National Institute of Health).

An early psychogenic theory, long disproved, proposed that emotionally cold mothers induce autism in children. Other possible causes, including diet and digestive-tract changes, have been proposed but not proven. However, we know for sure that autism is highly heritable. An identical twin of someone with autism is 70 times more likely to develop the condition than an unrelated individual.

But, how have genes that predispose one to autism survived? Autism inhibits abilities to form relationships, which would reduce one’s chances of having children and passing on these genes. One possible explanation is that autism genes are co-inherited with genes for certain cognitive talents – and this is where engineers and scientists come in.

Baron-Cohen and colleague Sally Wheelwright discovered a correlation between incidence of autism and familial relation to engineers, noting in a 1997 study that 12.5 per cent of fathers of autistic children were engineers, compared with only 5 per cent of fathers of children without autism, and 21.2 per cent of grandfathers of children with autism were engineers, compared with only 2.5 per cent of grandfathers of children without autism.

Hypothesis

So, the hypothesis is that some/many technical-minded people carry genes for autism in addition to the genes underlying their technical talents. They themselves do not display symptoms of severe autism but their children may get a double dose of autism genes – technical-minded people tend to fall for other technical-minded people. If the hypothesis is true, autism should be more common in places where a concentration of technical-minded people live, and indeed he has shown that autism rates in Eindhoven, the Silicon Valley of the Netherlands, are three times higher than in other similar-sized Dutch cities.

Autistic children display obsessive behaviours, eg memorising timetables. Baron-Cohen claims that all these behaviours are examples of “systemising”, analysing a system to discover its rules.

Baron-Cohen points out that strong systemising is more common in men than women. Testosterone plays a major role in “masculinising” the developing brain and a male foetus produces much more testosterone than a female foetus.

He says we cannot conclude that all technical-minded people carry genes for autism and any link with systemising is unlikely to explain the complexity of autism genetics. But genes for autism may overlap with genes allowing us to see beautiful patterns in nature, technology, maths and music.

William Reville is an emeritus professor of biochemistry and public awareness of science officer at UCC.

[ understandingscience.ucc.ie ]