I've no wish to complicate matters, but I know someone who was diagnosed with dyslexia and went on to get a degree. To answer QuizmasterG, these sort of problems DO have degrees of severity, as with dyspraxia, autism and so on.
Wildwood - you're making wild guesses there. The intelligence of the parents has no medical bearing on whether a child'll be dyslexic or not, and autism, which is largely misunderstood, has now been attributed to children who, in the past, were classed as just being "slow". In fact, American research indicates that the parents or grandparents are liable to be professional people, who've often worked in the engineering line.