Dyslexia. That's the first I've heard that.
I don't know whether it's true or not.
There is grammar check on this website. I use it a lot, sometimes a double a word or miss one out. It's because i plan what i write before writing it, so I miss out small words like "for" and "know" etc. Also letters.
(I searched the symptoms of it that's why I'm knowing this).
Also for the 15 and 51.
I mixed the 51 and 15 in my Latex but luckily i noticed it before i posted it.
The reason why I done this (i think) is because i worked on a question before it with 14/15 and this question was 14/51.