A Sweden study has found a statistically significant monotonic association between advancing grandpaternal age at the time of birth of the parent and risk of autism in grandchildren.
Men who had fathered a daughter when they were 50 or older were 1.79 times more likely to have a grandchild with autism, while men who had fathered a son when they were 50 or older were 1.67 times more likely to have a grandchild with autism, compared with men who had fathered children when they were 20 to 24 years old.
The results are consistent with mutations or epigenetic alterations associated with advancing paternal age, but the overall risk remains low.