
An important warning sign for possible ASD is having poor social skills. The Centers for Disease Control has a list of "red flags" including some underdeveloped social skills to watch for.
Recent research has identified a child’s failure to respond when his name is called as an important marker for ASDs. At twelve months most children will respond at least by turning their head when their name is called once or twice. It is suggested that if the child of that age exhibits such a failure to respond, the parent should watch for other social skill abnormalities. Of course, the child may also have hearing impairment.
Another marker is inattention to what is going on around him, or having expressionless looks.
Again, the earlier that children with ASD can be identified, the more likely that social deficits can be ameliorated somewhat.