Take a look back at the year’s notable papers and hot topics in autism research, plus Spectrum’s standout stories and quotes.

Autism is a chameleon: What it looks like changes from one person to the next. Individual differences crop up both in its core features and in the conditions that often accompany it: depression, epilepsy, anxiety and attention deficit hyperactivity disorder.

No one knows exactly what lies at the root of autism — but that hasn’t stopped scientists from speculating.

How clinical genetics is giving families long-sought answers and transforming autism care.

Take a look back at the year’s hot topics, notable papers and top Spectrum stories, plus innovative programs and artists changing how we view autism.

How is autism diagnosed? What explains the rise in autism’s prevalence? How much do genes contribute to the condition? What about the environment? This section provides answers to these and other questions.

It’s been five years since the autism community agonized over the debut of a new iteration of a diagnostic manual that set out to rewrite the definition of autism.

Problems with verbal and nonverbal communication — such as prosody, grammar, facial expressions and eye contact — contribute to the social difficulties individuals on the spectrum experience.

Mice of myriad strains and designs have helped scientists understand autism, but they have limitations as autism models. This report describes what scientists can hope to learn from old and new mouse models of autism.

Autism and attention deficit hyperactivity disorder often co-occur. Researchers are examining when and why these conditions may overlap.