[Dynamic mutation and its molecular cytogenetics].

Abstract

Dynamic mutation, the mechanism of allelic expansion of the heritable unstable triplet repeat DNA sequences, has been the subject of intense investigation since its discovery in 1991 as the molecular basis for fragile X syndrome. The fundamental distinction between dynamic and other forms of mutation is that dynamic mutation is a process rather than a single event. The process involves a relationship between the copy number of perfect repeat DNA sequence and its instability which accounts for the anticipation seen in families carrying a dynamic mutation disease. Recently, dynamic mutation due to allelic expansion of minisatellite repeats has also been demonstrated as either the fragile sites and a genetic disease. In this minireview, dynamic mutations associated with chromosomal fragile sites and their cytogenetics are overviewed.