Clinical features, psychological and academic profiles of Prader-Willi syndrome:  comparison of genetic subtypes

D. Greco¹, S. Buono¹, P. Occhipinti¹, A. Costanzo¹, L. Ragusa¹, G. Maiorana¹, F. Scannella¹, P. Bosco², and C. Romano¹

Department for ¹Mental Retardation and ²Department of Laboratories, Oasi Institute (IRCCS), Via Conte Ruggero,73 - 94018 Troina (EN)- ITALY

           Advances in genetics have led to an increased understanding of the role of the genotype on psychological functioning in Prader-Willi syndrome, in particular regarding cognitive and behavioral phenotype.  Besides it is important to study the phenotypes associated with the two genetic subtypes, deletion and maternal uniparental disomy.  Recent papers have reported phenotypic differences associated to these main genetic subtypes, including lower birth weight in the deletion group, shorter birth length in males with UPD and shorter course of gavage feeding and later onset of hyperphagia in females with UPD.  Other features previously reported with UPD were: less typical facial appearance, mild hypotonia, minor genital hypoplasia, skill with puzzles, high threshold of pain, and delay in diagnosis .

Cassidy, et al. (1997) reported relatively less impairment in articulation and skin picking among Prader-Willi individuals with UPD in comparison to those with deletion.  Roof, et al. (2000) and Thompson (2002) have examined differences in intellectual functioning related to the two genetic subtypes. They have reported that subjects with UPD had significantly higher verbal IQ scores than those with deletion, while performance IQ scores did not differ between the two PWS genetic subtypes.  It isn’t clear if these intellectual differences might influence school performance; however, Butler, et al. (2004) reported difficulties in reading and math skills as well as visual-motor integration in deletion group.

Dykens, et al. (1999) have found that the deleted cases showed significantly higher maladaptive ratings on Child Behavior Checklist as well as more symptom-related distress on the Yale-Brown Obsessive-Compulsive Scale.  Recently Butler, et al. (2004) confirmed more behavioral and psychological problems in individual with deletion.

            The purpose of this study is to examine the presence of such differences related to these two genetic subtypes in our sample.

June 2004