If there is an autistic child or sibling or other family member, is there reason for gene testing the family?

No: Genetic testing would not provide any additional benefit in predicting who else would be at higher risk for autism.

Possibly: If there is a known genetic abnormality in the person with autism, then family members of child-bearing age may benefit. Even if physical & neurological exam reveal no signs of a specific syndrome in a child with autism &/or intellectual disability, genetic microarray & dna probe for fragile x reveal an abnormality about 15% of the time. Evaluation by a geneticist is needed in those cases.

Test the child first: Before testing family members, have the child tested. there are many disorders that can present with autistic features. If an inheritable abnormality is found, then a discussion with a geneticist should be done to determine who might benefit from genetic testing.