AUTISM AND TUBEROUS SCLEROSIS

Autism and pervasive developmental disorders (PDD) are common in tuber ous sclerosis (TSC). The frequency of autism is about 25%, with 40-45% of TSC cases meeting criteria for autism or PDD. Among autistic popul ations, the frequency of TSC is 1-4% and perhaps as high as 8-14% amon g the subgroup of autistic individuals with a seizure disorder. Mental retardation (MR) and seizures, particularly infantile spasms, are sig nificant risk factors in the development of autism/PDD in TSC; however , neither are sufficient or necessary for the development of these beh aviors. The mechanism underlying the association of autism and TSC is as yet unclear but clinical features and neuroimaging investigations s uggest that an abnormal TSC gene may directly influence the developmen t of autism rather than it being a secondary effect of seizures or MR. The presence of autism/PDD may arise if the TSC gene mutations occur at critical stages of neural development in neural tissue of brain reg ions critical in the development of autism.