Parents who have a child with autism have almost a one in five chance of their next child having the condition too, a new study suggests.
The finding comes from a study of 664 children in the USA, Canada and Israel, and were published online in the journal Pediatrics.
“This is the largest study of the siblings of children with autism ever conducted. There is no previous study that identified a risk of recurrence that is this high,” said Sally Ozonoff, leader of the study and a professor of psychiatry and behavioural sciences in the US.
The likelihood of a baby who has an older sibling with autism developing the disorder used to be thought to be between 3% and 10%.
This new study, however, revealed that the overall rate of autism among all of the 664 participants was higher, at 18.7%.
In families where more than one child had autism, the recurrence rate was 32.2%, reports the Daily Mail.
“It is important to recognise that these are estimates that are averaged across all of the families. So, for some families, the risk will be greater than 18%, and for other families it would be less than 18%,” Sally added.
“At the present time, unfortunately, we do not know how to estimate an individual family’s actual risk,” she said.