© Martinez-Agosto Laboratory, Department of Human Genetics, University of California, Los Angeles, 2008-2015.

 

Autism-Macrocephaly

Description:
Autism comprises a clinically heterogeneous group of disorders - collectively referred to as "autism spectrum disorders" (ASD) - that share common features of impaired social relationships, impaired language and communication, and repetitive behaviors or a narrow range of interests. For most children with autism, symptoms develop gradually, although approximately 30% have a "regressive" onset usually between ages 18 and 24 months. About 50%-70% of children with autism are identified as mentally retarded by nonverbal IQ testing and approximately 25% develop seizures. Autism can be considered complex (i.e., presence of dysmorphic features and/or microcephaly) or essential (i.e., absence of physical abnormalities and microcephaly). About 25% of children who fit the diagnostic criteria for ASD at age two to three years subsequently begin to talk and communicate, and by age six to seven years blend to varying degrees into the regular school population. The remaining 75% have lifelong disability requiring intensive parental, school, and social support.

Testing:
Autism has many etiologies, a concept that was widely embraced following the discovery of the molecular basis of Rett syndrome in 2006. Since then autism has been documented in hundreds of neurologically based syndromes with multiple causes, outcomes, and treatment responses. Currently, a genetic etiology can be identified for between 15% and 20% of individuals with autism; in the others the cause remains unknown.

More information:
Autism-Macrocephaly

Macrocephaly (head circumference greater than the 97th centile), found in approximately 30% of children with autism, does not strongly correlate with outcome or IQ [Miles et al 2000] though Lainhart noted an association with delay in acquisition of first words [Lainhart et al 2006].