My son has very bad, very tiny, printed (as opposed to cursive) writing that is difficult to read but he thinks he has terrific writing, will even come show me "how good his writing is". [Not] He's 20 years old by the way. He was diagnosed with Asperger's at 12 years old but should have diagnosed before the age of 3 with Autism (but now it's all Autism anyway).
I on the other hand have beautiful, very easy to read, cursive writing (I have been complimented on it for many, many years, all the way back to 5th grade, and I also am on the spectrum.
And yet my son can't read it, he can't read anyone's cursive.
So I guess there could be a tie-in, the one poster mentioned another condition that can be a co-morbid diagnosis and I have no reason to doubt that.
I hope this helps! Have a great day!!
Diane
PS: My dad has very bad handwriting (he's on the spectrum - he's 69 now) and he owned and personally ran several successful businesses so good handwriting isn't a "hold-back" any longer like it used to be in "olden" days...