This is a supplement to project 5R01MH081845-04. This supplement provides funds for the examination of 5 pairs of age- and gender-matched post-mortem brain tissue specimens from the Autism Tissue Bank. The researcher will test the hypothesis that differences in the expression and/or regulation of heparan sulfate (HS, a protein found on the neuronal cell membrane) could significantly disrupt neural development, altering neurodevelopmental trajectories and contributing to the phenotypes associated with autism spectrum disorder (ASD). They will use a fluorescence immunohistochemical protocol to measure HS levels in brain tissue and perform microarray expression analysis on any HS-related genes found to be differentially expressed in patients vs healthy controls. The overall goals are to increase our understanding of the pathophysiological processes underlying ASD and to advance the development of heparan sulfate and/or HS-related genes as potential markers of ASD risk.