Cognitive profile in a large French cohort of adults with Prader-Willi syndrome: differences between genotypes.
Adults with the PWS deletion type show stronger visual problem-solving skills than the non-deletion type.
01Research in Context
What this study did
Doctors tested 120 French adults with Prader-Willi syndrome. They split the group by genetic type: deletion or non-deletion.
Each adult took the full WAIS IQ test. The team compared scores between the two gene groups.
What they found
The deletion group scored higher on Performance IQ. They also did better on puzzles and picture tasks.
Both groups still had mild to moderate intellectual disability. The gap was about one standard deviation.
How this fits with other research
Bruns et al. (2004) saw the same pattern six years earlier. Their smaller UK sample also showed deletion carriers winning on visuospatial tasks.
The two studies line up well. Both used the same IQ test and both found the same shape of strengths and weaknesses.
Poppes et al. (2010) simply adds more people and confirms the earlier picture. No contradictions appear.
Why it matters
When you write an education plan, check the genetic report. If the client has the deletion type, lean into visual schedules, puzzles, and hands-on tasks. Save dense verbal instruction for the non-deletion group. This small tweak can make lessons feel easier on Monday morning.
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02At a glance
03Original abstract
BACKGROUND: Prader-Willi syndrome (PWS) is a rare genetic disorder characterised by developmental abnormalities leading to somatic and psychological symptoms. These include dysmorphic features, impaired growth and sexual maturation, hyperphagia, intellectual delay, learning disabilities and maladaptive behaviours. PWS is caused by a lack of expression of maternally imprinted genes situated in the 15q11-13 chromosome region. The origin is a 'de novo' deletion in the paternal chromosome in 70% of the cases and a maternal uniparental disomy in 25%. The two main genotypes show differences, notably regarding cognitive and behavioural features, but the mechanisms are not clear. This study assessed cognitive impairment in a cohort of adults with genetically confirmed PWS, analysed their profiles of cognitive strengths and weaknesses, and compared the profiles in terms of genotype. METHODS: Ninety-nine male and female adults participated, all inpatients on a specialised unit for the multidisciplinary care of PWS. The Wechsler Adult Intelligence Scale (WAIS-III) was administered to all patients in identical conditions by the same psychologist. Eighty-five patients were able to cope with the test situation. Their scores were analysed with non-parametric statistical tools. The correlations with sex, age and body mass index were explored. Two genotype groups were compared: deletion (n = 57) and non-deletion (n = 27). RESULTS: The distribution of intelligence quotients in the total cohort was non-normal, with the following values (medians): Full Scale Intelligence Quotient (FSIQ): 52.0 (Q1:46.0; Q3:60.0), Verbal Intellectual Quotient (VIQ): 53.0 (Q1:48; Q3:62) and Performance Intellectual Quotient (PIQ): 52.5 (Q1:48; Q3:61). No correlation was found with sex, age or body mass index. Comparison between groups showed no significant difference in FSIQ or VIQ. PIQ scores were significantly better in the deletion group. The total cohort and the deletion group showed the VIQ = PIQ profile, whereas VIQ > PIQ was observed in the non-deletion group. The subtest scores in the two groups showed significant differences, with the deletion group scoring better in three subtests: object assembly, picture arrangement and digit symbol coding. Some relative strengths and weaknesses concerned the total cohort, but others concerned only one genotype. DISCUSSION: We documented a global impairment in the intellectual abilities of a large sample of French PWS patients. The scores were slightly lower than those reported in most other studies. Our data confirmed the previously published differences in the cognitive profiles of the two main PWS genotypes and offer new evidence to support this hypothesis. These results could guide future neuropsychological studies to determine the cognitive processing in PWS. This knowledge is essential to improve our understanding of gene-brain-behaviour relationships and to open new perspectives on therapeutic and educational programmes.
Journal of intellectual disability research : JIDR, 2010 · doi:10.1111/j.1365-2788.2010.01251.x