Adult onset focal dystonia and temporal discrimination : pathogenetic mechanisms, genes and environment

Orateur : Michael HUTCHINSON (University College Dublin)

The causes of adult onset isolated focal dystonia (AOIFD) are unknown ; it is considered a genetic disorder with autosomal dominant transmission and markedly reduced penetrance. We consider abnormal temporal discrimination to be mediational endophenotype in AOIFD indicating gene carriage and illuminating disease mechanisms. We hypothesise that the efficiency of temporal discrimination is a measure of effective temporal tuning in the superior colliculus / basal ganglia and relates to GABAergic inhibitory mechanisms. We consider that this is a disorder of brainstem (superior colliculus) and basal ganglia mechanisms for covert attentional orienting. Temporal discrimination and sex ratios in adult onset dystonia phenotypes show similar patterns of age-related sexual dimorphism and probably reflect age-related sexual dimorphism in cerebral (ambient) GABA. As well as sex- and age-related effects on the penetrance of both abnormal temporal discrimination and adult onset dystonia, environmental factors significantly affect both disease penetrance and AOIFD phenotype expression.

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