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Cognitive scores in carriers of huntington's disease gene compared to noncarriers
Author(s) -
Foroud Tatiana,
Siemers Eric,
Kleindorfer Dawn,
Bill Danield J.,
Hodes M. E.,
Norton James A.,
Conneally P. Michael,
Christian Joe C.
Publication year - 1995
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410370516
Subject(s) - huntington's disease , wechsler adult intelligence scale , allele , population , psychology , trinucleotide repeat expansion , disease , intelligence quotient , degenerative disease , rating scale , cognition , audiology , medicine , genetics , psychiatry , gene , biology , developmental psychology , environmental health
Huntington's disease (HD) is progressive neurodegenerative disorder recently shown to be due to an excess number of CAG trinucleotide repeats in the 5' translated region of chromosome 4. One of the cardinal features of HD is cognitive decline. While mental deterioration is obvious later in the disease course, the time of its onset is difficult to determine precisely. A sample of at‐risk individuals without signs or symptoms of HD by self‐report was studied. The Wechsler Adult Intelligence Test—Revised and a neurological rating scale were administered. The genotypes of 394 individual were then determined by polymerase chain reaction testing. On all portions of the WAIS‐R test, the mean score of the HD gene carriers was lower than that of the noncarriers. Scores on two of the performance subtests, the digit symbol and the picture arrangement, were significantly different in the two groups, even after the scores from all gene carriers who were diagnosed as affected based on their neurological motor examination were removed. The scores for the gene carriers on the various subtests were negatively correlated with the number of CAG repeats in the expanded HD allele. Such a relationship was not seen with the normal alleles of the noncarriers. Taken together, our results suggest that a deficit in cognitive function is an early finding of HD and that in this patient population, the degree of cognitive deficit is proportional to the number of CAG repeats in the HD allele.