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CAG-repeat length and the age of onset in Huntington disease (HD): a review and validation study of statistical approaches
Journal article   Open access   Peer reviewed

CAG-repeat length and the age of onset in Huntington disease (HD): a review and validation study of statistical approaches

Douglas R Langbehn, Michael R Hayden, Jane S Paulsen and PREDICT-HD Investigators of the Huntington Study Group
American journal of medical genetics. Part B, Neuropsychiatric genetics, Vol.153B(2), pp.397-408
03/05/2010
DOI: 10.1002/ajmg.b.30992
PMCID: PMC3048807
PMID: 19548255
url
https://www.ncbi.nlm.nih.gov/pmc/articles/3048807View
Open Access

Abstract

CAG-repeat length in the gene for HD is inversely correlated with age of onset (AOO). A number of statistical models elucidating the relationship between CAG length and AOO have recently been published. In the present article, we review the published formulae, summarize essential differences in participant sources, statistical methodologies, and predictive results. We argue that unrepresentative sampling and failure to use appropriate survival analysis methodology may have substantially biased much of the literature. We also explain why the survival analysis perspective is necessary if any such model is to undergo prospective validation. We use prospective diagnostic data from the PREDICT-HD longitudinal study of CAG-expanded participants to test conditional predictions derived from two survival models of AOO of HD. A prior model of the relationship of CAG and AOO originally published by Langbehn et al. yields reasonably accurate predictions, while a similar model by Gutierrez and MacDonald substantially overestimates diagnosis risk for all but the highest risk participants in this sample. The Langbehn et al. model appears accurate enough to have substantial utility in various research contexts. We also emphasize remaining caveats, many of which are relevant for any direct application to genetic counseling.
Models, Theoretical Trinucleotide Repeats Prognosis Prospective Studies Humans Middle Aged Peptides - genetics Male Models, Statistical Peptides - metabolism Age of Onset Aged, 80 and over Huntington Disease - genetics Adult Female Huntington Disease - diagnosis Aged Longitudinal Studies

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