title: Williams syndrome: a relationship between genetics, brain morphology and behaviour.
abstract: BACKGROUND
  Genetically Williams syndrome (WS) promises to provide essential insight into the pathophysiology of cortical development because its ∼28 deleted genes are crucial for cortical neuronal migration and maturation. Phenotypically, WS is one of the most puzzling childhood neurodevelopmental disorders affecting most intellectual deficiencies (i.e. low-moderate intelligence quotient, visuospatial deficits) yet relatively preserving what is uniquely human (i.e. language and social-emotional cognition). Therefore, WS provides a privileged setting for investigating the relationship between genes, brain and the consequent complex human behaviour.
  
  
  METHODS
  We used in vivo anatomical magnetic resonance imaging analysing cortical surface-based morphometry, (i.e. surface area, cortical volume, cortical thickness, gyrification index) and cortical complexity, which is of particular relevance to the WS genotype-phenotype relationship in 22 children (2.27-14.6 years) to compare whole hemisphere and lobar surface-based morphometry between WS (n = 10) and gender/age matched normal controls healthy controls (n = 12).
  
  
  RESULTS
  Compared to healthy controls, WS children had a (1) relatively preserved Cth; (2) significantly reduced SA and CV; (3) significantly increased GI mostly in the parietal lobe; and (4) decreased CC specifically in the frontal and parietal lobes.
  
  
  CONCLUSIONS
  Our findings are then discussed with reference to the Rakic radial-unit hypothesis of cortical development, arguing that WS gene deletions may spare Cth yet affecting the number of founder cells/columns/radial units, hence decreasing the SA and CV. In essence, cortical brain structure in WS may be shaped by gene-dosage abnormalities.
authors: Institute of Psychology, Faculty of Social Sciences and Politics, University of Lausanne, Lausanne, Switzerland. cherine.fahim@unil.ch
authors: C
authors: C
authors: Fahim
authors: U
authors: U
authors: Yoon
authors: N H
authors: NH
authors: Nashaat
authors: A K
authors: AK
authors: Khalil
authors: M
authors: M
authors: El-Belbesy
authors: A
authors: A
authors: Mancini-Marie
authors: A C
authors: AC
authors: Evans
authors: N
authors: N
authors: Meguid
mesh_terms: D000293:Adolescent; D002540:Cerebral Cortex / Q000473:pathology*; D002648:Child; D002652:Child Behavior; D002675:Child, Preschool; D003071:Cognition / Q000502:physiology; D005625:Frontal Lobe / Q000473:pathology; D018628:Gene Dosage / Q000235:genetics*; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics / Q000473:pathology / Q000523:psychology; D008279:Magnetic Resonance Imaging; D009483:Neuropsychological Tests; D009778:Occipital Lobe / Q000473:pathology; D010296:Parietal Lobe / Q000473:pathology; D010641:Phenotype; D013702:Temporal Lobe / Q000473:pathology; D018980:Williams Syndrome / Q000235:genetics / Q000473:pathology / Q000523:psychology