About 5 to 10 percent of American children are diagnosed as dyslexic. Historically, the label has been assigned to kids who are bright, even verbally articulate, but who struggle with reading -- in short, whose high IQs mismatch their low reading scores. When children are not as bright, however, their reading troubles have been chalked up to their general intellectual limitations.

Source: fMRIs show that dyslexia isn't a matter of IQ