Williams syndrome: a relationship between genetics, brain morphology and behaviour.
JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2012;
56:879-894. [PMID:
22044458 DOI:
10.1111/j.1365-2788.2011.01490.x]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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.
CONCLUSION
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.
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