Dyslexia is a fashionable disease and a small industry amongst the western middle classes. In reality the disease is restricted to very few people and consists in the brain interpreting writing that which is from left to right as from right to left. So a dyslexic person would read 'god' as 'dog'. The fashion arises as an excuse for children who are slow with their reading.
The inability to read as other children of the same age do is not seen for what it is - bad teaching, deficient initiation or just a perfectly natural and acceptable longer span of absorption of the particular skills that go into reading. It has to be put down to a brain defect. Hence the rush to dyslexia clinics, which eventually do succeed in teaching children to read and cite their success as proof that the dyslexia existed and was scientifically 'cured'.
A boy in my class at school had a very selective dyslexic manifestation (common to many Indians). He would read and say 'sk' as 'ks' and the other way round. So 'ask' would always be 'aks'. We would ask [or 'arks'] him to say "the eskimo escaped with extra whisky". 'Exclamation' with its 'kskl' Gordian knot was an impossibility.
The evidence that this inability to negotiate an 'x' can become permanent is to be found in the forms of the name which different languages have for the Macedonian Prince and conqueror - Alexander. He is called 'Sikander' as he moves through Arabia and Persia to the Punjab, dyslexising the 'ks' into 'sik'. Further East in the stronghold of Urdu, a language which has made a game of linguistic accuracies, he undergoes the further indignity of being metamorphosed to 'Iskander'.
(A column on Indian words in common use in Indian cities.)