Analysis of cerebral shape in Williams syndrome

Background: As a neurobehavioral disorder with a specific neurocognitive pr ofile and a well-defined genetic etiology, Williams syndrome (WMS) provides an exceptional opportunity to examine associations among measures of behav ior, neuroanatomy, and genetics. This study was designed to determine how c erebral shape differs between the brains of subjects with WMS and those of normal controls. Subjects: Twenty adults with clinically and genetically diagnosed WMS (mean +/- SD age, 28.5 +/- 8.3 years) and 20 healthy, age- and sex-matched contr ols (mean +/- SD age, 28.5 +/- 8.2 years). Design: High-resolution structural magnetic resonance imaging data were use d for shape-based morphological analysis of the right and left cerebral hem ispheres and the corpus callosum. Statistical analyses were performed to ex amine group differences. Results: Both right and left cerebral hemispheres of subjects with WMS bend to a lesser degree in the sagittal plane than normal controls (P < .001). The corpus callosum also bends less in subjects with WMS (P = .05). In;addi tion, subjects with WMS have decreased cerebral (P < .001) and corpus callo sum (P < .001) midline lengths. Conclusions: Subjects with WMS have significantly different cerebral shape from normal controls, perhaps due to decreased parieto-occipital lobe volum es relative to frontal regions. The similar observation in the corpus callo sum may be associated with a decreased size of the splenium in WMS. These f indings may provide important clues to the effect of genes in the WMS-delet ed region on brain development.