Trinucleotide repeat diseases - antecipation diseases

Dynamic mutations involve expansion of the number of repeat units consisting of three or more nucleotides in tandem (i.e. adjacent to one another) present in a gene or in its neighborhood. These repeats may occur in different genes and may code for different aminoacids. According to expansions sizes, it is possible to have unaffected individuals that are carriers of a pre-mutation. Instability of triplet repeat size can lead to gradual expansion through generations, a phenomenon called anticipation. Genetic anticipation is characterized by the reduction in the age of disease onset and by a worsening of symptoms in affected individuals in successive generations. This work describes dynamic mutations giving emphasis on triplet repeats diseases, making the parallel with disease anticipation. Treatment strategies that have been developed during the last years are also discussed.