When do signs of autism first appear? passed mchat but was diagnosis with hfa at 3 years. other than late talking, other signs didn't appear till 2.8 years.

Not specific: Autism is a disorder of appropriate social and verbal development. It may present in infancy as a defect in social awareness and eye contact, or later in childhood with regression in verbal language and inability to tolerate social settings. Some acquire autism due to injury, infection, or other neurological disease. Once signs are apparent, good therapy is necessary at any age.

Early recognition: Symptoms of autism can be recognized as early as six months.Lack of smiling, lack of response to your voice , and other subtle signs may bean early indication of autism.

First two years: Autism is a disorder, first diagnosed by leo kanner in the 1940's characterized by a lack of social and emotinal relatedness, there is no social smiling, no recognition of important people, ie mother. Often they have blank stares. Poor reaction to shange, prefer things to stay the same. Stereotypical and repetitive movements (finger flap) and repetitive vocalizations. Dsm5 may change things.