It's listed as a common comorbid in the OASIS book about Asperger's syndrome.
I recieved a huge amount of flack from my teachers growing up because of how bad my handwriting was and how slow my writing was. In things like spelling tests, I had to write as quickly as I possibly could, just to keep up with the teacher... then they would yell at me (or worse, count even correctly spelled words wrong) because of the handwriting.
In middle school, I got a portable electronic typewriter, which helped things a lot (the spelling teacher liked the lack of a spell check, too), and word processors became more common by the time I got to highschool.
That didn't stop one English teacher from failing be due to handwriting, though. I ended up having to make up the course through a community college, who placed me in second semester college English (even though I was only a high school sophomore at the time).