Dynamic mutation: possible mechanisms and significance in human disease.

Increases in repeat-DNA copy number are the molecular basis of a growing list of human genetic diseases, including fragile X syndrome, myotonic dystrophy, Huntington disease and a form of epilepsy. Repeat-DNA sequences undergo a unique process of dynamic mutation, the common properties of which probably reflect common molecular events. This form of mutation is no longer restricted to trinucleotide repeats, because repeats of different length have been found to undergo expansion.