DS1 has a friend who "was" dyslexic. He was dyslexic all through his UK junior school. He left at the end of yr5 to move with his family to America.
When the family went to meet the head at the new school and discuss the boy's SN they were told "we don't have dyslexia in the US" and that he would be treated just like any other child, according to his ability.
Anyway boy is now back in the UK, in yr8 and does indeed no longer have dyslexia. Apparently all his difficulties in spelling and reading have resolved themselves and he's meeting all the national levels he should be.
So, what happened?