|Abstract: ||The purpose of this lecture is to review the current knowledge on the complex pattern of psychoeducational and neurocognitive deficits in the 22q11.2 microdeletion syndrome (Velocardiofacial syndrome VCFS, DiGeorge syndrome DGS).
Children with VCFS show IQ scores (FSIQ) in the range of borderline intellectual abilities to moderately learning disabled. Early reports find no association between cognitive ability and the presence of cardiac malformations (Swillen et al., 1997). The only contributing factor identified to date to the variability in intelligence in VCFS is the presence of a de novo versus familial occurrence of the deletion (Swillen et al., 1997).
The intelligence profile is often characterized by a higher verbal IQ (VIQ) than performance IQ (PIQ). However, this verbal/performance IQ divergence is not consistent across all individuals with VCFS, and it is not uncommon to find individuals who do not demonstrate this pattern or, conversely, exhibit the opposite pattern. Interestingly, the VIQ/PIQ discrepancies have been more observed among children and adolescents with VCFS than in adults with the syndrome. These findings could indicate an atypical development in childhood of the skills involved in these particular measures, where the visuo-spatial abilities develop at a slower rate than their peers while their verbal abilities remain stable (Campbell & Swillen, 2005).
Within the domain of academic achievement, reading and spelling are relative strengths in VCFS but mathematics pose a problem for many individuals with VCFS. On-going neurocognitive research suggests that the impairment in mathematical ability may be associated with poor visual-spatial skills. Simon et al.(2005) recently demonstrated that children with del22q11.2 (compared with siblings, and with typically developing children) performed more poorly on tests of visual attentional reasoning, visual enumeration and relative magnitude judgement. Neuroimaging investigations indicate that these skills may all depend critically on the inferior parietal lobes, which seems to be dysfunctional in the del22q11.2 syndrome.
Further neuropsychological investigations of the cognitive problems have also identified deficits in visual-spatial memory and in planning.
To conclude, although the delineation of the cognitive phenotype in del22q11.2 is progressing, still many questions have to be asked and answered. Future studies should focus on the variability in cognition, and on the developmental trajectory of cognitive skills in children with del22q11.2.
Campbell, L., & Swillen, A. (2005). The cognitive spectrum in velo-cardio-facial syndrome. In K. C. Murphy & P. J. Scambler (Eds.), Velo-Cardio-Facial Syndrome: A model for understanding microdeletion disorders (pp. 147-164). Cambridge: Cambridge University Press.
Simon, T. J., Bearden, C. E., McDonald-McGinn, D., & Zackai, E. (2005). Visuospatial and numerical cognitive deficits in children with chromosome 22q11.2 deletion syndrome. Cortex, 41, 145 155.
Swillen, A., Devriendt, K., Legius, E., Eyskens, B., Dumoulin, M., Gewillig, M., & Fryns, J. P. (1997). Intelligence and psychosocial adjustment in Velocardiofacial Syndrome: A study of 37 children and adolescents with VCFS. Journal of Medical Genetics, 34, 453 458.