The neurocognitive phenotype of the 22q11.2 deletion syndrome: selective deficit in visual-spatial memory

The 22q11.2 deletion syndrome (velocardiofacial/DiGeorge syndrome) is associated with a high frequency of learning disabilities. Although previous work has demonstrated that verbal skills are typically better preserved than non-verbal skills on both IQ and academic achievement testing in children with this syndrome, such measures are not sufficiently specific to determine a selective cognitive deficit. As part of an ongoing prospective study of patients with this syndrome, 29 children aged 5-17 with confirmed 22q11.2 deletions were assessed with a comprehensive neuropsychological test battery, including matched tasks of verbal and visuospatial memory. Results indicate that 22q patients displayed a selective deficit in visual-spatial memory, which was mirrored by deficits in arithmetic and general visual-spatial cognition. Further, a dissociation between visual-spatial and object memory was observed, indicating further selectivity of this pattern of deficit, and providing evidence for the dissociability of these components of visual cognition. These results indicate that children with 22q11.2 deletions display a specific neurocognitive phenotype, and suggest that this region of Chromosome 22q11 may harbor a gene or genes relevant to the etiology of nonverbal learning deficits.