Autism spectrum disorders and inborn errors of metabolism: an update.

Background: Autism spectrum disorder is characterized by social communicative deficits with restricted interests occurring in about 1% of the population. Although its exact cause is not known, several factors have been implicated in its etiology, including inborn errors of metabolism. Although relatively uncommon, these disorders frequently occur in countries with high rates of consanguinity and are often associated with behavioral problems, such as hyperactivity and aggression. The aim of this review is to examine the association of autism with these conditions.

Method: A computer-assisted search was performed to identify the most common inborn errors of metabolism associated with autism.

Results: The following disorders were identified: phenylketonuria, glucose-6-phosphatase deficiency, propionic acidemia, adenosine deaminase deficiency, Smith-Lemli-Opitz syndrome and mitochondrial disorders, and the recently described branched chain ketoacid dehydrogenase kinase deficiency.

Conclusion: The risk of autistic features is increased in children with inborn errors of metabolism, especially in the presence of cognitive and behavioral deficits. We propose that affected children should be screened for autism.