Grandparents 'may relay autism risk to grandchildren'

The risk of developing autism may be passed on through - and not just to - future generations, researchers say.

The international study suggests older fathers are more likely to have grandchildren with autism than their younger counterparts.

The mechanism is unclear but it is thought they may transmit "silent mutations" to their grandchildren.

But experts have urged caution, stressing autism is the result of many different factors.

The study, looking at almost 6,000 people with the condition, is published in the journal Jama Psychiatry.

According to the National Autistic Society, more than one in every 100 people in the UK have the condition.

Previous studies suggested older fathers may be at greater risk of having children with autism than younger dads.

But the team of UK, Swedish and Australian researchers say this is one of the first pieces of evidence to show the risk can be passed on through - rather than just straight to - future generations.