• While we know that genes contribute to the development of autistic disorder, the specific genes have not yet been identified. Changes in the genes that lead to autistic disorder may be inherited from the mother or the father, or may be new changes in the individual with autistic disorder. We have two copies of most of our genes. Some genes are only active when inherited from our mother, and some genes are only active when inherited from our father. This is called imprinting. It is possible that an imprinted gene or genes is involved in autistic disorder, however none have been identified so far.

Asperger Disorder
Individuals with Asperger disorder do not have a delay in spoken language development, but can have serious deficits in social and communication skills.

Pervasive Developmental Disorder Not Otherwise Specified (PDD/NOS)
Is a diagnosis often considered for children who show some signs of autistic disorder, but who do not meet the specific diagnostic criteria for the other PDDs.

Rett Disorder
Rett disorder is among the most common genetic cause of profound intellectual and physical disability in girls, occurring more commonly than 1 in 10,000 female births.

Childhood Disintegrative Disorder
Children with childhood disintegrative disorder develop normally for a relatively prolonged period before developing a condition that resembles autistic disorder.