Whilst I wouldn't say that either myself or Ds1 has this, both of us have very strong traits as part of our ASDs, though Ds1 falls closer to the definition than I do as he also has the understanding difficulties.
Basically, with myself it goes:
1: Learned to read early, had reading age of 13 when I was 7.
2: Very prolific reader from a young age, can read 2 - 3 novels a day, though with children this is usually reduced to one a day.
3: Fascinated with letters and a bit with numbers, although I am crap at maths. Will count number of es on a page, or go down the sentences looking for the alphabet in order. Will choose codewords in puzzle books as a favourite.
4: Will focus on words written down and think of alternatives for them. Will count the number of letters in them. Will hyperfocus on things like the difference between could, should, ought and must.
5: Will write or think alphabetical lists of topics, eg animals or types of food.
6: Will repeat poems in my head, counting the syllables in the poem as I do so.
Ds1:
1: He is reading very well for his age in terms of physically understanding the letters, but struggles to understand even the basic concept of many of his stories. He will focus on particular words in the story and ask what they mean, but unless the book is very clear he won't pick up on a lot of what is happening.
2: He loves writing and will focus on certain things, often names of children in his class, and can spend literally hours writing words. His writing is neater than mine
. He will copy passages from stories that he likes over and over - Mr Tickle being a recent example.
3: He loves numbers and has been fascinated by them since he was tiny. He'll count out the numbers on our street and until recently many places in town were known by a number.
4: He is starting to ask what individual words mean and has been fascinated with alliteration, even setting himself "homework" to continue with it this week, so I think that he is also picking up on a fascination with words and how they sound and their meaning as well.