A STUDY OF THE HUNTINGTONS-DISEASE ASSOCIATED TRINUCLEOTIDE REPEAT INTHE SCOTTISH POPULATION

Accurate measurements of a specific CAG repeat sequence in the Hunting ton's disease (HD) gene in 337 HD patients and 229 normal controls fro m the Scottish population showed a range from 3S to 62 repeats in affe cted subjects and eight to 33 in normal subjects. A link between early onset of symptoms and very high repeat number was seen. For HD patien ts with the most common affected allele sizes (39 to 42 repeats) absol ute repeat size was a poor index for the age at onset of symptoms. The re was variability in the transmitted repeat size for both sexes in th e HD size range. We observed a significant increase of repeat size for paternal transmission of the disease and greater instability for pate rnally transmitted CAG repeats in the HD size range.