Abstract
BackgroundPrader-Willi Syndrome (PWS) is a complex neurogenetic disorder with symptoms involving not only hypothalamic, but also a global, central nervous system dysfunction. Previously, qualitative studies reported polymicrogyria in adults with PWS. However, there have been no quantitative neuroimaging studies of cortical morphology in PWS and no studies to date in children with PWS. Thus, our aim was to investigate and quantify cortical complexity in children with PWS compared to healthy controls. In addition, we investigated differences between genetic subtypes of PWS and the relationship between cortical complexity and intelligence within the PWS group.MethodsHigh-resolution structural magnetic resonance images were acquired in 24 children with genetically confirmed PWS (12 carrying a deletion (DEL), 12 with maternal uniparental disomy (mUPD)) and 11 age- and sex-matched typically developing siblings as healthy controls. Local gyrification index (lGI) was obtained using the FreeSurfer software suite.ResultsFour large clusters, two in each hemisphere, comprising frontal, parietal and temporal lobes, had lower lGI in children with PWS, compared to healthy controls. Clusters with lower lGI also had significantly lower cortical surface area in children with PWS. No differences in cortical thickness of the clusters were found between the PWS and healthy controls. lGI correlated significantly with cortical surface area, but not with cortical thickness. Within the PWS group, lGI in both hemispheres correlated with Total IQ and Verbal IQ, but not with Performance IQ. Children with mUPD, compared to children with DEL, had two small clusters with lower lGI in the right hemisphere. lGI of these clusters correlated with cortical surface area, but not with cortical thickness or IQ.ConclusionsThese results suggest that lower cortical complexity in children with PWS partially underlies cognitive impairment and developmental delay, probably due to alterations in gene networks that play a prominent role in early brain development.
Highlights
Prader-Willi Syndrome (PWS) is a rare and poorly understood neurodevelopmental disorder that affects 1 in 15.000 live births
Since neuronal migration and the resulting cortical thickness, number of cortical columns, cortical surface area, neuronal growth and establishment of cortico-cortical connections are probable underlying factors contributing to gyrification [11,12,13], it is plausible that aberrant early brain development and neuronal migration in children would lead to deviant cortical folding patterns in children with PWS
LGI in PWS and healthy controls Differences in Local gyrification index (lGI) between children with PWS and healthy controls are presented in Figure 1 and Table 2
Summary
Prader-Willi Syndrome (PWS) is a rare and poorly understood neurodevelopmental disorder that affects 1 in 15.000 live births. Only two quantitative structural MRI studies have been performed in adults with PWS. These studies found smaller grey matter volumes in the frontal, temporal and parietal lobes [7,8] and smaller white matter volumes in the frontal and temporal cortices, brainstem, and cerebellum [8]. Sylvian fissure polymicrogyria was reported in adult patients with PWS in a qualitative structural MRI study [9], suggesting aberrant development of cortical folding in patients with PWS. Prader-Willi Syndrome (PWS) is a complex neurogenetic disorder with symptoms involving hypothalamic, and a global, central nervous system dysfunction. We investigated differences between genetic subtypes of PWS and the relationship between cortical complexity and intelligence within the PWS group
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