• Researchers compare genetic material from people with autistic disorder and their families to find common shared pieces of genetic material. Once researchers narrow the areas of chromosomes where suspected genes associated with autistic disorder are, they can search for candidate genes in the area. Candidate genes are genes that, based on their known function or location, may be associated with autistic disorder. Once candidate genes are identified, further studies are done to prove or disprove an association with autistic disorder and to better understand the gene's structure and function.

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.