[Williams syndrome. A summary of cognitive, electrophysiological, anatomofunctional, microanatomical and genetic findings].
Williams syndrome (WS) is the result of a hemideletion of about 17 genes in the q11.22-23 region of chromosome 7. Patients with WS show unique phenotypic features that include elfin face, heart malformations, calcium metabolism problems and learning disorders. The latter consist of mental retardation that is characterised by serious difficulties with processing visuospatial tasks, a striking ability to easily recognise faces, a relatively developed linguistic capacity and sensitiveness to sound, a strong need to establish affective ties with other people and a fondness for music. Anatomical studies show a decrease in the postero-dorsal parts of both hemispheres of the brain, malformation in the central dorsal region and an expansion of the superior temporal gyrus, of the amygdala and of the frontal lobe. These macroscopic anomalies are accompanied by microscopic anomalies, which consist of changes in the number and size of the neurons. Studies on evoked potentials show acoustic hyperexcitability and abnormal waves related to language and to faces. Genetic studies in our laboratories show that the exact size of the deletion can vary, which means partial cases also exist and have partial phenotypes. Combining behavioural, electrophysiological, anatomical and genetic reports suggests a problem with the posterior dorsal region of the brain, possibly resulting from mistakes in establishing the dorsoventral and caudorostral genetico-molecular gradients, which specify the cortical regions during development.
Galaburda
A M
AM
Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA. agalabur@caregroup.harvard.edu
Holinger
D
D
Mills
D
D
Reiss
A
A
Korenberg
J R
JR
Bellugi
U
U
D001519:Behavior; D003071:Cognition; D004594:Electrophysiology; D005071:Evoked Potentials; D006801:Humans; D008279:Magnetic Resonance Imaging; D018980:Williams Syndrome / Q000235:genetics / Q000473:pathology / Q000503:physiopathology / Q000523:psychology