Psychopathologic Disorder in Prader-Willi Syndrome     

S. Buono, D. Greco, F. Scannella, P. Occhipinti, L. Ragusa, A. Costanzo, C. Romano

Department for Mental Retardation, Oasi Institute (IRCCS), Via Conte Ruggero,73 - 94018 Troina (EN)- ITALY

Prader-Willi syndrome (PWS) is a genetic disorder that results from the absence of normally active paternally expressed genes from the 15q11-q13 chromosome region. The majority of individuals (70%) have a paternally derived interstitial deletion of 15q11-q13, while 25% have maternal disomy 15 (UPD), and the remaining 2% to 5% of individuals have imprinting defects.  Among the phenotypical characteristics observed are: delayed psychomotor development, generalized hypotonicity, commonly retarded intellectual development, behavioral and emotional problems and hyperphagia, with resulting obesity.

The data in literature indicate an association between PWS and psychopathological characteristics.  Persons with PWS can present with generalized developmental delay together with cognitive deficits. During their development emerge behavioral problems. In almost all cases, self injurious behaviors (skin-picking), as well as stubbornness and repetitive behaviors, are present. Frequently, there are problems linked to the emotional affective sphere, for instance, there is a significant emotional lability consisting in irascibility and scarce tolerance of frustrations. Rigidity in thought processes may also be present, consisting at times in manipulative modalities expressed in interpersonal relationships, as well as in polemical and oppositional attitudes. Furthermore, frequent compulsive and self injurious behaviors, as well as considerable difficulty in anxiety management, are evidenced. Advances in genetics have led to an increased understanding of the role of the genotype on psychological functioning in particular regarding the cognitive and behavioral phenotype. 

Our work examines a sample composed of 18 persons with PWS, whose ages range from 2 to 35 years and whose intellectual disability levels vary as follows: slight mental retardation (45%), moderate mental retardation (11%), NOS mental retardation (16%), psychomotor delay (16%), borderline intellectual functioning (6%), normal intellectual functioning (6%). Furthermore, 45% of the persons with PWS examined manifested psychopathological problems.  Butler et al. (2004) have reported that the individuals with deletions generally have more behavioral and psychological problems than individuals with UPD.  In our sample we have examinated the presence of such differences related to these two genetic subtypes. Our study shows that the individuals with deletion have more psychopathological disorders than persons with UPD.