How to make a diagnosis of Autism ?

It is a difficult job to diagnose ASD or Autism spectrum disorders.This ASD manifests in early child hood.So basically is a pediatric age group disorder that is related to brain.

No particular tests diagnoses ASD for sure, so the diagnosis is made on the feedback of people who have watched the child continuously for a period of time. Developmental assessment is also necessary to make a diagnosis.

According to CDC ASD's toll is around 1 in 150. As ASD is a band a group or rather a process in evolution many have less symptoms as they are not affected much. So features of classical autism may well be absent, in other words many might be in a sub-clinical phase.
Reserchers in Washington university have associated autism with hearing problems and gastrointestinal problems, this further complicates the matter in 2 ways.
1.Diagnosis becomes difficult as both of these are quite common place in pediatric age group.
2.Autism spans more than brain, is disturbing in itself.
Age of diagnosis is quite variable, as it is based on observations, so not only it depends on the manifestations of the child, which is ironically altered by the diseases process itself, but also by the clinical acumen of the care givers.But most of the cases can be diagnosed around 5 years.
Language and communication problems lead to social impairment. this can include avoidance of eye contact. Avoiding human contact like cuddling, or not acceptance of daily routine modifications can be early warning signs for the parents.When in you are going in for well-baby visits try to remember the mile stones of development like social smile, single word, phrase, sitting, waliking etc.
9 months, 18 months and 24 months and 30 months milestones are to be properly taken during each well-chil visits. This screening helps the pediatrician to catch developmental delays and can point to autism.
Asperger's syndrome is a mild variety of autism, with today's standardized screening tools it is possible to suggest but not fully diagnose autism. these screening tools comprise of questionnaires and different types of checklists.
The second phase which can definitively diagnose the disease are the following
1.The Childhood Autism Rating Scale
2.The Autism Diagnosis Interview
3.The Gilliam Autism rating Scale
Earlier screening is required if a sibling has been affected.
Normally when one hears the diagnosis it upsets. But earlier the diagnosis, better the prognosis as definitive interventions can be taken early.

See the video by cnn How to know autism