Normally, I would say that if you can't trust your tester with the info, you need a new tester.
I agree with this.
Are you only having the WISC, or also other testing? If you want to rule the autism in/out you should get a wider battery of tests.
If your sole goal is an IQ score, knowing about the autism dx would possibly matter in how the testing report is written. FWIW our neuropsych told us that IQ scores tend to go up and become more coherent after autism has been remediated for a time; this suggests to me that you may not get an accurate score for a relatively young child with autism. It's better to know this going in. And probably better for your tester to know what s/he's dealing with in terms of the accuracy of the scores, as well.
DeeDee
