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THE MOLECULAR BASIS OF HUNTINGTON'S DISEASE.

Huntington's disease was recently found to be associated with a repeating pattern of nucleotide bases (CAG) on chromosome 4. This study analyzed the sensitivity and specificity of this defect as a marker for inheritance of Huntington's disease.

Researchers determined the length of the CAG repeat in 1007 Huntington's patients from 43 national and ethnic groups, 300 healthy controls with no family history of neuropsychiatric disorders, and 113 patients with personal or family histories of other neuropsychiatric disorders. Among the Huntington's patients, 98.8 percent had 36 to 121 CAG repeats on the affected allele. Conversely, 99.1 percent of control chromosomes (those from healthy controls plus the unaffected alleles from Huntington's patients) had 10 to 29 repeats, and less than 1 percent had 30 to 39 repeats. Finally, all patients with a personal or family history of other disorders had numbers of CAG repeats within the normal range (26 or fewer).

Comment: The length of the CAG repeat is a highly sensitive and specific marker of the inheritance of Huntington's disease. However, the mechanism by which CAG repetition leads to Huntington's disease is not yet known.

— AS Brett

Published in Journal Watch General Medicine May 31, 1994

Citation(s):

Kremer B et al. A worldwide study of the Huntington's disease mutation. N Engl J Med 1994 May 19 330 1401-1406.

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