Cortical Thickness and ASD in 22q11.2 Deletion Syndrome; An International Collaboration
Objectives: We wished to establish whether variation in CT is associated with comorbid ASD in 22q11DS individuals.
Methods: We included 73 individuals with 22q11DS (23 males and 34 females), aged between 6 and 33 years (mean age=14, SD=6). Of these, 36 individuals met diagnostic criteria for ASD based on the ADI-R & ADOS. The resulting two groups (i.e. 22q11DS+ASD & 22q11DS-ASD) did not differ significantly on age or IQ. Participants underwent structural T1-weighted magnetic resonance imaging (MRI) at the Institute of Psychiatry, Psychology and Neuroscience, London & The Semel Institute for Neuroscience, UCLA. CT was measured using FreeSurfer (http://surfer.nmr.mgh.harvard.edu). Vertex-wise statistical analysis of CT measures were estimated by regression of a GLM including group as categorical fixed effect factor. A random-field-based cluster-threshold (p<0.05) was applied to correct for multiple comparisons (Worsley 1999).
Results: Individuals with 22q11DS+ASD, when compared to 22q11DS-ASD, had significantly increased cortical grey matter thickness in 2 right hemisphere brain areas; the inferior frontal gyrus (BA47) & postcentral gyrus (BA43)(Fig. 1).
Conclusions: This is the first known study to indicate that absence or presence of comorbid ASD is associated with genetically determined variation in cortical morphometry. Future research is required to determine how genetic variation within the deleted region determines outcome.