HG-GAM KNOCK-OUTS 1 Running head: HB-GAM KNOCK-OUTS Neuroanatomical Characteristics of Mice Deficient in Heparin Binding Growth Associated Molecule (HB-GAM)

Pervasive Developmental Disorder (PDD) is a categorical term used to classify disorders in which the patient suffers deficits in three main domains: language, behavior and social skills. Heparin Binding Growth Associated Molecule (HB-GAM) is an extracellular protein involved in neurite outgrowth and radial migration. Mice deficient in HB-GAM demonstrate deficits in cognition, behavior and social skill similar to what is seen in PDD patients. Furthermore, PDD patients have been found to have brain abnormalities in the limbic system; amygdala, hippocampus, entorhinal cortex and cerebellum. Based on the idea that brain abnormalities are highly correlated with abnormal behavior, the present study focused on the neuroanatomy of the entorhinal cortex of mice deficient in HBGAM. It was observed that mice deficient in HB-GAM show abnormal neuroanatomy similar to that seen in human PDD brains: tightly packed small neurons in entorhinal cortex layer IV. From these findings, we propose that HB-GAM Knock-outs may be a good mouse model for human PDD.