International del22q11.2 meeting edition:5th location:Marseille, France date:10-12 July 2006
Early studies on intelligence in children and adolescents with a del22q11.2 syndrome (VCFS/DGS) reported IQ scores ranging from borderline intelligence to moderately learning disability (Swillen et al., 1997; Moss et al., 1999; Woodin et al., 2001). Early reports find no association between cognitive ability and the presence of cardiac malformations. 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).
While these prior studies were important first steps towards understanding the cognitive outcome in del22q11.2 syndrome and the variability in intelligence, they were limited by small sample sizes and the use of different measures for intelligence. Also, longitudinal data on the cognitive trajectory of children with del22q11.2 are lacking.
Therefore, we studied the cognitive abilities in a large sample (n = 103; 56 male, 47 female; mean age 7;9 years; all tested by using the age-appropriate Wechsler Intelligence Scales) and following factors that could contribute to the variability in intelligence: de novo versus familial deletion; gender; congenital heart defect (CHD); and (child)psychiatric diagnosis.
In addition, we will present longitudinal data on 27 children and adolescents with a del22q11.2.
For the total group (n=103) mean full scale IQ (FSIQ) was 73.48 (SD 11.73; range 50-109).
A significant VIQ > PIQ discrepancy was found ( t(102)=5.69, p <.01). There is no overall effect of gender or CHD, neither was there a Gender x CHD interaction on IQ. However, children who inherited the deletion from a parent (familial deletion) had a significant lower FSIQ (63.89; SD 8.02) compared to children with a de novo deletion (mean FSIQ 74.65; SD 11.64). Also, children with a diagnosis of autism spectrum disorder (ASD) (n= 19) had a significant lower FSIQ (68.73; SD 10.26) compared to the children with no ASD (n = 84; mean FSIQ 74.56; SD 11.83).
Longitudinal data were collected on 27 subjects (16 male, 11 female). All subjects were tested at least 2 times with the Wechsler scales. Mean time interval between T1 and T2 was 48.33 months (4 years). A decline in IQ of 5.33 points (SD 10.86) between T1 and T2 was observed, which is a statistically significant difference (student T-test p < .03).
There was no effect of CHD, but an effect of gender. Girls tend to have a greater decline in FSIQ between T1 and T2 compared to boys. However, these results must be interpreted with caution (small sample, time interval in both groups (girls and boys) was different) and should be replicated in larger samples.
In future, additional factors such as size of the deletion, genetic polymorphisms (COMT, PRODH), parental IQ, SES, and (other) environmental factors will also be included in analyses.