Conversation so far:
in dear john what is wrong with the dad
In the 2010 film Dear John, Savannah mentions to John that his father may have a form of high-functioning autism known as Asperger's syndrome.
what are the characteristics of asperger's syndrome
Characteristics of Asperger syndrome include problems with social interactions and restricted and repetitive behavior.
how many people are diagnosed with asperger syndrome
In 2015, Asperger syndrome was estimated to affect 37.2 million people globally.

Question: when do signs first appear
Self-contained rewrite: when do signs of asperger syndrome first appear