All signs do not have to be present for a diagnosis of autism spectrum disorder, but children must have difficulties in both A and B. The signs can vary widely in severity, but must impair children's functioning.

A. Difficulties in social communication and interaction:

• Difficulty engaging with others and sharing thoughts and feelings

• Difficulty with nonverbal communication (such as making eye contact, understanding and using body language and facial expressions)

• Difficulty developing, maintaining, and understanding interpersonal relationships

B. Restricted, repetitive patterns of behavior, interests, and/or activities:

• Repeated movements or speech

• Inflexible adherence to routines and resistance to change

• Very restricted, intense interests

• Very increased or decreased response to physical sensations, such as tastes, smells, textures