Pervasive developmental disorders in Prader-Willi syndrome: the Leuven experience in 59 subjects and controls

Area of Science:

• Neurodevelopmental Disorders
• Genetics and Behavior

Background:

• Prader-Willi syndrome (PWS) is a complex genetic disorder with a known behavioral phenotype.
• The co-occurrence of Pervasive Developmental Disorder (PDD) in PWS has not been extensively studied.
• Understanding the overlap between PWS and autism spectrum disorders is crucial for diagnosis and intervention.

Purpose of the Study:

• To investigate the co-morbidity of Pervasive Developmental Disorder (PDD) in individuals with Prader-Willi syndrome (PWS).
• To compare the prevalence of PDD in PWS individuals with a matched control group of non-specific mentally retarded individuals.
• To explore potential risk factors for PDD within the PWS population.

Main Methods:

• A cohort of 59 individuals with PWS and 59 matched controls (IQ, gender, age) were assessed.
• The Pervasive Developmental Disorder Mentally Retardation Scale (PDD-MRScale), based on DSM-III-R criteria, was administered.
• Statistical analysis was performed to compare PDD diagnosis rates and identify associated factors.

Main Results:

• A significant autistic-like behavioral phenotype was observed in the majority of PWS individuals, particularly in language, communication, and imaginative play.
• Nineteen percent of the PWS group met the full diagnostic criteria for PDD, compared to 15% in the control group.
• Higher IQ in PWS did not prevent PDD development, and genetic origin (uniparental disomy/imprinting mutation) appeared to be a risk factor.

Conclusions:

• The findings highlight a substantial intersection of autistic symptomatology within the PWS behavioral phenotype.
• This study suggests that obsessive-compulsive behaviors in PWS should be considered within the broader spectrum of autism disorders.
• Genetic factors related to PWS may increase the risk for developing genuine PDD.