Prenatal diagnosis of autism is not possible. Autism is observed approximately four times more frequently in boys than in girls, and the reason for this gender difference is not yet fully understood. The diagnosis of autism is not made through laboratory tests or imaging methods. The diagnostic process involves a detailed observation of the child by a child psychiatrist, a comprehensive anamnesis taken from the family, and the application of standardized developmental tests. For differential diagnosis and the evaluation of possible co-occurring conditions, blood tests, neurological examination, ENT check-up, or consultations from other specialist areas for metabolic diseases may be requested if necessary.