Dyslexia

Dyslexia was a condition which made it difficult for certain people to read or write. (TV: The Hungry Earth)

History
When the Eleventh Doctor met Elliot Northover in 2020, he discovered that Eliot was dyslexic. The Doctor used Leonardo da Vinci and Albert Einstein as examples for Elliot to see that being dyslexic did not mean that you couldn't do great things. Elliot told the Doctor he preferred to listen to audio books instead of reading, and the Doctor encouraged him to continue trying. (TV: The Hungry Earth, Cold Blood)

When Josephine Jones thought that the Doctor believed her to be stupid, the Doctor explained that he'd been keeping track of all his former companions. He noted that she had a thirteenth grandchild on the way and that the child would be dyslexic, but a good swimmer. (TV: Death of the Doctor)