Once a conclusive biological trace has been identified, be it at the gene or protein level, this could be used at any point in development from before birth right through to adulthood. But unless the current diagnostic accuracy improves, there would be profound ethical concerns.
A large percentage of parents would almost certainly use a prenatal autism test to make a decision on whether to terminate the pregnancy – if the statistics for Down's syndrome since the introduction of prenatal screening are anything to go by. It is believed that around 90% of pregnancies in England and Wales that receive a diagnosis of Down's syndrome are aborted.
The existence of a prenatal screening test would also have implications for potential treatments. There are currently no drugs for treating autism disorder but in the near future, various hormonal treatments may become available. If clinicians were tempted to start medical intervention very early, there would be concerns about side effects in the unborn child. If the diagnosis proved to be faulty, the consequences of these decisions could have lasting effects.
"The best case use of a prenatal test at the moment would be if you could say to a parent, your child has got an 80% likelihood of autism and so once the baby's born, we would like to keep a close eye on that child in case they need extra support like speech therapy or social skills training or some sort of behavioural approach," Baron-Cohen says.
"That would mean that there were no potential side effects and you might be able to intervene at a much younger age. So from an ethical point of view, if there was a screening test, using it for early intervention via a psychological approach would be quite risk-free and could carry a lot of benefit."