Background: Prader-Willi syndrome (PWS) is a genetically determined neurodevelopmental disorder that is associated with the under-expression of maternally imprinted genes at the 15q11-q13 chromosomal locus. In addition to a characteristic physical and behavioural phenotype, those with the syndrome have impaired social cognition, literal mindedness and inflexibility. The present authors investigated the relationship between the PWS cognitive and behavioural phenotype, educational experience, and levels of attainment in reading, writing and arithmetic.
Methods: All subjects from a population-based sample of people with PWS, augmented by those with PWS living in other regions together with a contrast group of people with learning disability (LD) of other aetiologies, are included in the present study. Those children over 3 years of age whose families consented or adults who themselves consented were assessed for ability and attainment (over 7 years of age), and information on functional ability was also obtained from an informant. Underachievement was defined as the difference between the score predicted from full-scale IQ and the actual achievement score.
Results: Commonly, levels of achievement were lower than would have been predicted on the basis of IQ among those in the groups with PWS and LD. In the group with PWS, underachievement across academic domains was positively correlated with the percentage of time in education in a special school and negatively correlated with Vineland Socialization domain standard score. There were no across-domain significant correlations in the group with LD. When using multiple regression analysis, the percentage of time in special school was the only predictor of underachievement and only in the group with PWS. However, some children with PWS in special schools did achieve as expected in at least one academic domain.
Conclusions: Children with PWS may be placed in special schools largely because of their behavioural problems or physical disabilities, or expectations based on their PWS status. Their intellectual abilities may well be masked by their immature social behaviour. The present authors propose that a failure to recognize and address the specific educational needs which follow from this combination of poor socialization skills and complex maladaptive behaviours, in the context of relatively mild LD, may explain their findings.