Abstract
1.Abstract:
Fragile sites show susceptibility to DNA damage, leading to alterations that contribute to cancer development. They are associated with accumulation of unstable AT- and CCG-repeats which lead to unusual secondary structures and an increase in flexibility as well as instability. With the selfish gene hypothesis, which postulates that each gene tend to optimize its own replication, it seems like a paradox that these unstable sequences even exist because they represent an evolutionary disadvantage and should therefore be disfavoured by natural selection.
This disadvantage would be compensated for if these fragile sites were linked to or involves a repair gene that prevents instability/breakage. Fragile sites and repair genes should therefore be in linkage in the genome. It is basically two ways of understanding this: either that fragile sites infiltrate DNA repair genes, or that DNA repair genes have a mutation bias that causes expansion of unstable sequences in and around these genes. Either way one would think that these repair genes would have a high repeat content. The aim of this study was to make a map for linkage between DNA-repair genes and fragile sites as a preliminary study and then to scan these genes for CCG- repeat sequences.