The molecular basis of common and rare fragile sites.

Fragile sites are specific loci that form gaps and constrictions on chromosomes exposed to partial replication stress. Fragile sites are classified as rare or common, depending on their induction and frequency within the population. These loci are known to be involved in chromosomal rearrangements in tumors and are associated with human diseases. Therefore, the understanding of the molecular basis of fragile sites is of high significance. Here we discuss the works performed in recent years that investigated the characteristics of fragile sites which underlie their inherent instability.