Eleven affected males and one carrier female were found to have a fragile site
on the X chromosome (fra(X)(q27)).
The underlying DNA structure of fragile sites
appears to make them particularly prone to breakage and hence to being jettisoned from the cancer genome.
Population cytogenetics of folate-sensitive fragile sites
Folate sensitive fragile site
expression seems to appear as a result of heritable defects of DNA methylation along a region normally binding a folding protein involved in chromosome condensation.
, chromosome regions that are prone to break apart or suffer mutations, appear to be weak links in the chain of events that guides development from embryo to adult.
We have previously shown that oncogene activation (and therefore cell transformation) is associated with DDR activation at fragile sites
(Di Micco, Nature 2006).
The findings that miRNAs were frequently located at cancer-associated genomic regions, including fragile sites
, prompted these investigators to propose that miRNA genes were a new class of genes involved in human tumorigenesis (2).
Key words: dog, mammary tumors, cytogenetic, fragile sites
Possible correlations between chromosome breakpoints other than 9 and 22 in these Ph variant tranlocations, and recent updates for the map locations of consistent cancer breakpoints, fragile sites
, and oncogenes are discussed.
The 22 articles in the 2007 edition of the annual series summarize recent developments in understanding cell cycle regulation of DNA replication, chromosome fragile sites
, the biology of Candida albicans, and transport of sequence-specific RNA interference information between cells.
The final tier includes subtelomeric FISH; comparative genomic hybridization; screening for folate-sensitive fragile sites
, 7-dehydro-cholesterol, and the UBE3A gene; and an extended metabolic work-up.
Known weak links in DNA chains are often broken in tumor cells, suggesting that such fragile sites
on chromosomes may foster a variety of cancers (154: 317).