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Prader-Willi syndrome: intellectual abilities and behavioural features by genetic subtype
Katja M Milner1, Ellen E Craig, Russell J Thompson
1Child & Adolescent Psychiatry Department & MRC Social, Genetic & Developmental Psychiatry Centre, Institute of Psychiatry, London, UK.
Journal of Child Psychology and Psychiatry, and Allied Disciplines
|September 24, 2005
Summary
Individuals with Prader-Willi syndrome (PWS) due to uniparental disomy (UPD) showed more autistic-like impairments than those with a deletion. Paternally imprinted genes in chromosome 15q11-13 may be a risk factor for autism.
Area of Science:
- Genetics
- Neuroscience
- Developmental Biology
Background:
- Over-expression of paternally imprinted genes in chromosome 15q11-13 is implicated in autism etiology.
- Prader-Willi syndrome (PWS) provides a model to study this, with different genetic causes affecting these genes.
Purpose of the Study:
- To compare autistic-like impairments in PWS individuals with maternal uniparental disomy (UPD) versus deletion of the 15q11-13 region.
- To investigate if deletion size (Type I vs. Type II) influences cognitive and behavioral phenotypes in PWS.
Main Methods:
- Ninety-six individuals with PWS were assessed using standardized autism diagnostic tools (ADOS, ADI, ASQ) and other behavioral/cognitive measures (CY-BOCS, VABS, Wechsler, Mullen, Raven's).
- Participants were grouped into maternal UPD (n=49) or 15q11-13 deletion (n=47), with deletion subgroups for Type I (TI) and Type II (TII).
- Assessments were conducted blind to genetic status.
Main Results:
- UPD cases exhibited significantly higher levels of autistic-like impairments in social interaction compared to deletion cases.
- Few differences were observed between Type I (TI) and Type II (TII) deletion groups.
- Cognitive ability levels tended to be lower in the TI deletion group.
Conclusions:
- Findings support the hypothesis that paternally imprinted genes in the 15q11-13 region are a genetic risk factor for autistic symptomatology.
- These genes may play a role in the etiology of autism.
- No clear relationship was found between deletion size and the cognitive/behavioral phenotype, contrasting with some previous reports.