Chapter

The clinical phenotype of juvenile Huntington’s disease

Roger A. Barker and Ferdinando Squitieri

in Juvenile Huntington's Disease

Published on behalf of Oxford University Press

Published in print January 2009 | ISBN: 9780199236121
Published online November 2012 | e-ISBN: 9780191753213 | DOI: http://dx.doi.org/10.1093/med/9780199236121.003.0004
The clinical phenotype of juvenile Huntington’s disease

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JHD is a rare disorder affecting between 1% and 10% of patients who develop HD. It is typically inherited from the father (∼90% of cases) and is associated with large CAG repeats and can even present ahead of the affected parent. It typically presents as a combined behavioural, cognitive, and motor disorder, with the latter being dominated by rigidity and bradykinesia rather than chorea (the so-called Westphal variant) with a gait disorder. In addition patients can have major oro-phrayngeal problems with dysarthria along with ataxia, myoclonus, and epileptic seizures.

The clinical features of JHD vary, and the reported literature is small, so it is difficult to draw any firm conclusions. In particular, it is highly probable that cases presenting before the age of 10 years are different from those presenting in the second decade of life. Indeed Squitieri et al. have postulated a specific dosage effect of the mutation affecting the phenotype of very young patients. Nance et al. have proposed that the features of JHD at this age almost universally consist of a positive family history and two of the following features: declining school performance, seizures, oral motor dysfunction, rigidity, and gait disorder. However, older children may have a very similar presentation as well, although in general their signs and symptoms are more variable than those presenting under the age of 10 (see Table 4.2).

Until such time as a registry with prospective data is collected on large numbers of cases of JHD then it will be hard to move beyond the level of anecdote which is reflected in the discussions in this chapter.

Chapter.  3755 words. 

Subjects: Neurology

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