Hyperlexia is relatively rare. Children who are born with it learn to decode words at a very early age. They tend to be intensely interested in letters and how they combine to words. However, they have extremely low comprehension abilities.
Also seen is a deficit in reasoning and problem solving. These children, unfortunately, tend to have difficulties forming relationships with other children.
Extracted from “Overcoming Dyslexia” by Sally Shaywitz, M.D.