Asperger's syndrome (AS) is an autism spectrum disorder. It is milder than autism but shares some of its symptoms. It is more common in boys than girls. An obsessive interest in a single subject is a major symptom of AS. Some children with AS have become experts on dinosaurs, makes and models of cars, even objects as seemingly odd as vacuum cleaners. Their expertise, high level of vocabulary and formal speech patterns make them seem like little professors. Children with AS have trouble reading social cues and recognizing other people's feelings. They may have strange movements or mannerisms. All of these make it difficult for them to make friends. Problems with motor skills are also common in children with AS. They may be late learning to ride a bike or catch a ball, for example. Treatment focuses on the three main symptoms: poor communication skills, obsessive or repetitive routines, and physical clumsiness.