Huntington's disease and several of the spinocerebellar ataxias are caused by the abnormal
expansion of a CAG repeat within the coding region of the disease gene. This results in the
production of a mutant protein with an abnormally expanded polyglutamine tract. Although
these disorders have a clear monogenic cause, each polyglutamine expansion mutation is
likely to cause the dysfunction of many pathways and processes within the cell. It has been
proposed that the ubiquitin proteasome system is impaired in polyglutamine expansion …

The main histopathological feature of Huntington's disease (HD) is the presence of protein
aggregates that are gathered into inclusion bodies. So far the mechanisms that lead to
inclusion formation as well as their role in the pathogenesis of HD are not totally understood.
However, it is well established that inclusion bodies contain components of the ubiquitin-
proteasome system. Accordingly, it has been postulated that impairment of this machinery
can be one of the causes of this disorder. In this review, the authors summarize the state of …