I just found this article and thought it was worth noting, because I have been telling colleagues and parents that the discrepancy model is on its way out, but lately I couldn't put my finger on any one source. I have read it in several papers.
"As you might expect, early intervention gives the best results. Yet for decades most schools wouldn't consider special education for a child until he or she had fallen at least a year behind. That may be changing. Congress is considering legislation that would eliminate the need to show a discrepancy between a child's IQ and his or her achievements before receiving a diagnosis of dyslexia.
Ideally, all children should be screened in kindergarten—to minimize educational delay and preserve self-confidence. How do you know someone has dyslexia before he or she has learned to read? Certain behaviors—like trouble rhyming words—are good clues that something is amiss. Later you may notice that your child is memorizing books rather than reading them. A kindergarten teacher's observation that reading isn't clicking with your son or daughter should be a call to action.
If caught soon enough, can a child's dyslexia be reversed? The evidence looks promising. In her book, Shaywitz reports that brain scans of dyslexic kindergartners and first-graders who have benefited from a year's worth of targeted instruction start to resemble those of children who have never had any difficulty reading."
this is from Time magazine, and here is a link to the full article: