Huntington's disease: the challenge for cell biologists

Huntington's disease (HD) is one of eight inherited neurodegenerative diseases caused by expansions of (CAG)(n) tracts that encode polyglutamine segments in expressed proteins. Studies of pathogenic mechanisms for all these late-onset diseases suffer from a common drawback: experimental studies require massive acceleration of a process that, in affected humans, usually takes decades. But is the rapid-onset disease of transgenic mouse models and in cells the same as the slow-onset disease in humans? We review recent work on HD, noting several issues whose significance is likely to be crucial - but which are as yet unresolved. We discuss these in light of the distinction between disease-specific pathogenic mechanisms and artifacts of polyglutamine overexpression. We suggest that the initial stages of HD result from dysfunction rather than death, and we consider the potential discovery of compounds that might interfere with early pathogenic events.