Autism, AW tihz uhm, is a serious medical disorder that appears in young children and persists throughout life. It is characterized by limited ability to communicate and interact with other people. Some symptoms may be present in infancy, but the condition becomes more noticeable as affected children reach the age when their peers are beginning to speak in phrases and participate in social play. In the United States, autism and related disorders, Asperger syndrome and pervasive developmental disorder, occur in about 6 of every 1,000 births, or about 1 out of every 150 births. Boys are more commonly affected than girls.