1. Yes, GAI is 135, significantly higher than FSIQ, at a base rate of 0.9%, and well under p<.05 (difference of 8 is p<.05).
2. I can understand her wanting to chase the ASD to some extent, especially with Comprehension being notably lower than Voc and Sim, and perhaps anything she may have seen in his presentation and history that we can't see in these scores, but,
3. The extremely low Essay Composition scores, along with relative WMI and PSI weaknesses (we have discussed low WMI and PSI more extensively elsewhere), definitely warranted further eval of written expression. Did she include a TOWL-4? The absurdly large difference between Sentence Comp and Essay Comp usually says difficulty with idea generation and organization of written expression to me. His underlying writing skills are clearly solid, as he can write a sentence at a time, however, that does not translate into the skills necessary for consistent high school-level writing. EC is an opinion essay about your personal preferences. I suspect he had difficulty pinning down a legitimate opinion about a relatively trivial topic. It is also a moderately timed task, as you are only allowed 10 minutes to both plan and execute a brief essay.
I am curious as to whether subscores were listed for Sentence Comp. I find that students with difficulty with open-ended writing often do the best on Sentence Combining, slightly worse on Sentence Building, and then bomb Essay Comp.
An alternate interpretation of the discrepant Comprehension score might have to do with the less well-defined nature of that task, compared to the other two. While the evaluator was probably chasing the social comprehension aspect of it, he may actually have been struggling with the open-ended "why" nature of many of the items.
4. It also concerns me that there is a substantial difference between his oral reading accuracy when reading a list of single words, and when reading words in connected text, and attempting simultaneously to comprehend said text. Any indication that he read the word reading list any slower or faster? Or that he needed to re-read or slow down for the reading comprehension subtest? (Granted, if his miscalls are largely insignificant words, it may explain his high comprehension anyway.)
5. Reading achievement is grossly in line with his VCI, as mathematics is with his PRI, but PRI is notably higher than VCI, which would be consistent with expressive language relative weaknesses, feeding into written expression weaknesses, mostly in the form of difficulty with idea generation and organization.
The main thing I would hope for your son to have in his documentation that has not previously been mentioned is some reference to these last two elements of written expression (idea generation, organization). They are particularly important when you consider the kind of higher-level literary analysis and persuasive writing that is expected in upper-division HS English classes. His sporadic brilliant performance is probably closely related to his personal connection to essay topics, which enables him to generate ideas more freely, and to use context from his life experience and special interests to scaffold the organization of his writing. When it's an essay about some literary figure from an era or culture with little connection or relevance to him, he likely struggles greatly. I would suggest accommodations that include making explicit connections between writing topics and his personal experience and interests, priming the pump for idea generation with personally-relevant classroom discussion as part of his pre-writing activities, and the use of a variety of graphic organizers and concept maps to scaffold the organization of his writing.
