Abstract
Fifty‐nine cases with infantile autism/autistic disorder were subclassified according to associated medical condition (fragile‐X, tuberous sclerosis, neurofibromatosis, hypo‐melanosis of Ito, Moebius syndrome, Rett syndrome, and a ‘new’ syndrome associated with a marker chromosome). It was concluded that, even within a group of cases fitting currently accepted criteria for autism, there is considerable variation in symptom profile depending on the exact type of associated medical condition.