DS6 was reading sight words by 18 months and reading books (like the Mr Men series) by 2.5 years, although he understood what he read. He was a late talker, as in multiple word sentence speaker, but he could type sentences from two. I worried a little about him until he was two, when he gave me a hug; he didn't request affection, but happily received it. Other than that, I didn't see any traits in him that had me worried.
I would put him in the categories of hyperlexia II (minus any ASD traits) and also Einstein syndrome. Although he hasn't lost those "savant-like" skills.
