My Aspie son didn't score nearly as well on the comprehension subtest of the WISC as he did on the other verbal subtests - his comprehension subtest score was only average - but that didn't stop him from ending up with a 134 VCI, which is at the 99th percentile. His scores on the Reynolds (RIAS), which does not include social comprehension measures in the verbal section, were far higher - 147 verbal composite. So, one way to look at that difference is that the comprehension subtest alone depressed his verbal composite score nearly a full SD, but even depressed, it still fell squarely in the gifted range.
I will vouch for the idea that Aspergers can make it hard for a gifted child to show what they are capable of on some IQ tests. This is a very different thing from it making them not gifted, and it is something to be aware of when having a child on the spectrum evaluated.
