Dynamic mutation in Dutch Huntington's disease patients: increased paternal repeat instability extending to within the normal size range.

Analysis of the distribution of normal and expanded alleles of the polymorphic (CAG)n repeat in the IT15 gene in the Dutch population confirmed the presence of an expanded repeat on all Huntington's disease (HD) chromosomes. Our results show that the size distributions of normal and affected alleles overlap. Normal alleles range from 11 to 37 repeats and HD alleles contain 37 to 84 repeats. A clear correlation is found between age at onset and repeat length, but the spread of the age at onset in the major repeat range producing characteristic HD is too wide to be of diagnostic value. In the av... Mehr ...