Is it okay to explain about the disability to my child without the child's or family's permission?

As a rule, information about someone's disability, such as a diagnosis name, isn't passed to others without the person's and family's consent. When explaining to your child, it's enough to convey "what's difficult and how to help" in a general form, without giving a name or diagnosis. Confirm the specifics through the teacher, checking the child's and family's wishes.