Chapter

The diagnostic challenge

Oliver W. J. Quarrell and Martha Nance

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/9780199236121.003.0009
The diagnostic challenge

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The onset of HD is insidious. Most clinicians refrain from making a diagnosis of either adult or juvenile onset HD until motor signs are present. The motor signs in JHD may differ from those seen in the classical adult form of the condition. Children and young people from HD families may present with behavioural or emotional problems, and a question of whether these are part of the onset of JHD or have an alternative explanation arises. Some families, in this circumstance, have described this as a distressing time as they perceive that professionals are not listening to their concerns, or are even blaming their parenting skills for their child’s problems.

A problem has arisen because the genetic test is sometimes described as ‘diagnostic’. In fact the interpretation of the result depends on the clinical context in which the test was done. If unequivocal neurological abnormalities consistent with HD are present, then an abnormal result is seen as confirming a clinical diagnosis. If an abnormal test result is reported in an asymptomatic person, then the same genetic test is considered to be predictive. The problem comes when a child or young person has problems which may or may not be due to JHD. Unless the test results show an extremely large increase in CAG repeat length, an abnormal result will not resolve that difficulty.

Clinicians need to continue to use the genetic test cautiously in children and young people with behavioural and emotional problems alone, but must also be sensitive to the negative perceptions that this may generate for the parent and other carers. At present additional clinical information may be obtained from standard imaging and neuropsychological assessments, and in the future analysis of other biomarkers currently in development may help in the assessment of this clinical problem.

Chapter.  4952 words. 

Subjects: Neurology

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