Who is Annemarie from When You Reach Me and what is their importance?

Annemarie is a student in Miranda's class. When Miranda and Sal stop hanging out together, Miranda becomes friends with Annemarie. Annemarie also had a best friend, Julia, but the two of them also had a fight. Miranda eventually learns that Annemarie is epileptic and not supposed to eat bread, something she does on a daily basis with Miranda and Colin.