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Reduced penetrance alleles for Huntington's disease: a multi-centre direct observational study

Quarrell, Oliver W.J., Rigby, Alan S., Barron, L., Crow, Y., Dalton, A., Dennis, N., Fryer, A.E., Heydon, F., Kinning, E., Lashwood, A., Losekoot, M., Margerison, L., McDonnell, S., Morrison, P.J., Norman, A., Peterson, M., Raymond, F.L., Simpson, S., Thompson, E. and Warner, J. (2007) Reduced penetrance alleles for Huntington's disease: a multi-centre direct observational study Journal of Medical Genetics, 44, (3), e68-[6pp]. (doi:10.1136/jmg.2006.045120).

Record type: Article


Objective: To obtain penetrance data for Huntington’s disease when DNA results are in the range of 36–39 CAG repeats and assess the consistency of reporting the upper allele from two reference centres.
Method: Data were collected anonymously on age of onset or age last known to be unaffected from a cohort of individuals with results in this range. DNA samples were re-analysed in two reference centres. Kaplan-Meier analysis was used to construct an age of onset curve and penetrance figures.
Results: Clinical data and concordant DNA results from both reference centres were available for 176 samples; penetrance figures (and 95% confidence intervals) for this cohort, at age 65 and 75 years, were 63.9% (55.5% to 73.2%) and 74.2% (64.2% to 84.2%), respectively. Inclusion of 28 additional subjects for whom repeat DNA results were unavailable, obtained from only one reference centre, or discrepant by one repeat within this range, gave penetrance data (including 95% confidence intervals) at ages 65 and 75 years of 62.4% (54.4% to 70.4%) and 72.7.% (63.3% to 82.1%), respectively. 238 duplicate results were available from the reference centres; 10 (4.2%) differed by one CAG repeat in the reporting of the upper allele and in two (0.84%) of these cases the discrepancy was between 39 and 40 repeats.
Conclusion: When DNA results are in this range, a conservative approach is to say that there is at least a 40% chance the person will be asymptomatic at age 65 years and at least a 30% chance the person will be asymptomatic at age 75 years.

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Published date: 2007
Keywords: london, trinucleotide repeat, confidence intervals, disease, chromosomes, alleles, age of onset, children, england, scotland, ireland, australia, netherlands, dna, prediction, time, onset


Local EPrints ID: 60139
ISSN: 0022-2593
PURE UUID: 1d750206-045f-4ba3-8267-8e1cfd3ce692

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Date deposited: 08 Sep 2008
Last modified: 17 Jul 2017 14:23

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Author: Oliver W.J. Quarrell
Author: Alan S. Rigby
Author: L. Barron
Author: Y. Crow
Author: A. Dalton
Author: N. Dennis
Author: A.E. Fryer
Author: F. Heydon
Author: E. Kinning
Author: A. Lashwood
Author: M. Losekoot
Author: L. Margerison
Author: S. McDonnell
Author: P.J. Morrison
Author: A. Norman
Author: M. Peterson
Author: F.L. Raymond
Author: S. Simpson
Author: E. Thompson
Author: J. Warner

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