A reliable diagnosis can first be given at the age of two. At the age of 18 and 24 months, children should get a check-up. If anything wrong is noticed, a further evaluation is done. In this, a team of professionals will interview the child’s guardians about the child’s behaviour and see what they are like in different settings. This may also include behavioural or physical assessments as well as intelligence tests or developmental tests. A good, detailed, history of the child is often very useful in receiving a diagnosis.