Chromosome Fragile Sites

Chromosomal fragile sites are specific loci that preferentially exhibit gaps and breaks on metaphase chromosomes following partial inhibition of DNA synthesis. Their discovery has led to novel findings spanning a number of areas of genetics. Rare fragile sites are seen in a small proportion of individuals and are inherited in a Mendelian manner. Some, such as FRAXA in the FMR1 gene, are associated with human genetic disorders, and their study led to the identification of nucleotide-repeat expansion as a frequent mutational mechanism in humans. In contrast, common fragile sites are present in all individuals and represent the largest class of fragile sites. Long considered an intriguing component of chromosome…

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  FRAXA Research Foundation