Cerebellothalamocortical connectivity regulates penetrance in dystonia.
Dystonia is a brain disorder characterized by sustained involuntary muscle contractions. It is typically inherited as an autosomal dominant trait with incomplete penetrance. While lacking clear degenerative neuropathology, primary dystonia is thought to involve microstructural and functional changes in neuronal circuitry. In the current study, we used magnetic resonance diffusion tensor imaging and probabilistic tractography to identify the specific circuit abnormalities that underlie clinical penetrance in carriers of genetic mutations for this disorder. This approach revealed reduced integrity of cerebellothalamocortical fiber tracts, likely developmental in origin, in both manifesting and clinically nonmanifesting dystonia mutation carriers. In these subjects, reductions in cerebellothalamic connectivity correlated with increased motor activation responses, consistent with loss of inhibition at the cortical level. Nonmanifesting mutation carriers were distinguished by an additional area of fiber tract disruption situated distally along the thalamocortical segment of the pathway, in tandem with the proximal cerebellar outflow abnormality. In individual gene carriers, clinical penetrance was determined by the difference in connectivity measured at these two sites. Overall, these findings point to a novel mechanism to explain differences in clinical expression in carriers of genes for brain disease.
Argyelan
Miklos
M
Center for Neurosciences, The Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Manhasset, New York 11030, USA.
Carbon
Maren
M
Niethammer
Martin
M
Ulug
Aziz M
AM
Voss
Henning U
HU
Bressman
Susan B
SB
Dhawan
Vijay
V
Eidelberg
David
D
D000328:Adult; D001931:Brain Mapping; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000473:pathology*; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology*; D003198:Computer Simulation; D038524:Diffusion Magnetic Resonance Imaging; D004421:Dystonia / Q000000981:diagnostic imaging / Q000235:genetics / Q000473:pathology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D018832:Molecular Chaperones / Q000235:genetics; D009010:Monte Carlo Method; D009154:Mutation; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000473:pathology; D049268:Positron-Emission Tomography; D013788:Thalamus / Q000000981:diagnostic imaging / Q000473:pathology*
D018832:Molecular Chaperones; C108175:TOR1A protein, human