Trials have begun at Cardiff University to see if a drug that shrinks tumours could also help treat some forms of autism.
It is an unexpected side-effect of the medication which is used by people with the genetic disorder Tuberous Sclerosis Complex (TSC).
There are an estimated 500 people in Wales with TSC which causes non-malignant tumours to grow on the skin and in organs like the brain and kidney.
Sufferers are also more likely to have conditions such as epilepsy and autism.
A drug called Everolimus has been shown to shrink tumours in people with TSC and there is also anecdotal evidence that it improves their autism too.
Trystan James, 26, from Cross Hands in Carmarthenshire has the disease and is already taking the drug.
His mother Marie says it has reduced tumours on his face and also helped his autism.
The research at the Institute of Medical Genetics at Cardiff University will investigate the extent that the tumour-shrinking drug can help the brain function of TSC sufferers.
Professor Julian Sampson who is in charge of the study says it could help improve understanding of the causes of autism.
The study is expected to take up to two years to complete.