Prader-Willi syndrome--a study comparing deletion and uniparental disomy cases with reference to autism spectrum disorders.

Prader Willi Syndrome (PWS) is a neuro-genetic disorder. It has been reported that cases due to paternal deletion 15q11-13 (Del) behave differently to cases due to uniparental disomy (UPD). Comparison of the two forms of PWS has, to date, not included the frequency of autistic behaviours, even though there are reports of an association between maternal duplications of 15q11-13 and autism spectrum disorders (ASD). It was predicted that maternal UPD PWS cases would be more prone to ASD than Del PWS cases due to their duplicated maternally expressed genes. A preliminary test of the hypothesis was conducted using postal and telephone surveys of matched, genetically verified, UPD and Del cases using the Autism Screening Questionnaire (ASQ) and the Vineland Adaptive Behaviour Scales (VABS). As predicted, UPD cases were reported as exhibiting significantly more autistic symptomatology. They also were born to older mothers and were reported on the VABS to have more deficits in motor control problems and fewer adaptive skills in the Daily Living Skills domain. Del cases were reportedly more skilled at jigsaw puzzles. The results lend further support to the notion that abnormality in the expression of maternal imprinted 15q11-13 genes may confer a susceptibility to ASD. They also suggest that there may be cognitive differences between the groups in processing visuo-spatial information.