ABSTRACT
Extensive brain pathology has been documented in subjects with autism (Bauman and Kemper 2005). Multiple ¡ndings have been reported, including changes in brain growth, volume, and organization, highlighting the heterogeneous nature of autism. A consistent ¡nding is for postnatal accelerated brain growth, followed by relative growth arrest in childhood (Courchesne et al. 2003, 2007; Hazlett et al. 2005). Indeed, by mid-childhood, approximately 20% of children with autism display macrocephaly (Fombonne et al. 1999). However, macrocephaly has also been observed in the unaffected parents and siblings of autistic children with macrocephaly (Miles et al. 2000) and, as such, may represent a risk factor for autism rather than a pathological aspect of the disorder (Geschwind 2009).
