Downing NR, Lourens S, De Soriano I, Long JD, Paulsen JS. Phenotype Characterization of HD Intermediate Alleles in PREDICT-HD.
J Huntingtons Dis 2017;
5:357-368. [PMID:
27983559 DOI:
10.3233/jhd-160185]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND
Huntington disease (HD) is a neurodegenerative disease caused by a CAG repeat expansion on chromosome 4. Pathology is associated with CAG repeat length. Prior studies examining people in the intermediate allele (IA) range found subtle differences in motor, cognitive, and behavioral domains compared to controls.
OBJECTIVE
The purpose of this study was to examine baseline and longitudinal differences in motor, cognitive, behavioral, functional, and imaging outcomes between persons with CAG repeats in three ranges: normal (≤26), intermediate (27-35), and reduced penetrance (36-39).
METHODS
We examined longitudinal data from 389 participants in three allele groups: 280 normal controls (NC), 21 intermediate allele [IA], and 88 reduced penetrance [RP]. We used linear mixed models to identify differences in baseline and longitudinal outcomes between groups. Three models were tested: 1) no baseline or longitudinal differences; 2) baseline differences but no longitudinal differences; and 3) baseline and longitudinal differences.
RESULTS
Model 1 was the best fitting model for most outcome variables. Models 2 and 3 were best fitting for some of the variables. We found baseline and longitudinal trends of declining performance across increasing CAG repeat length groups, but no significant differences between the NC and IA groups.
CONCLUSION
We did not find evidence to support differences in the IA group compared to the NC group. These findings are limited by a small IA sample size.
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