HERITABLE TRINUCLEOTIDE REPEATS AND NEUROLOGICAL DISORDERS

In the past 3 years, seven human neurological disorders have been foun d to be associated with an abnormal number of unstable trinucleotide r epeats within exons or non-expressed regions of a gene. These forms of mutations are called dynamic mutations. The expansion in copy number of trinucleotide repeats may represent a large number of hereditary di sorders. The correlation between the length of the repeated size and t he disease severity and variable onset has provided some genetic expla nation for a phenomenon called anticipation. However, there are numero us questions which cannot be explained by anticipation. Many other fac tors such as genomic imprinting and variable DNA methylation may also contribute to the puzzling features of these phenotypes.