Chromosome Fragile Site
Chromosomes are the structures that hold genes. Genes are the individual instructions that tell bodies how to develop and keep the bodies running healthy. Fragile sites are heritable locations on chromosomes that have a tendency to break or appear as a gap or constriction when cells are exposed to certain chemical agents.
In humans, one fragile site is associated with the commonest X-linked (sex chromosome-linked) mental retardation. Fragile sites are classified as common (present in all people) or rare (present in at least 1 out of 20 people and heritable). A few rare fragile sites are induced by depletion of folate/thymidine; bromodeoxyuridine (a drug that causes breaks in chromosomes and has been proposed as an antiviral and antineoplastic agent; used in the treatment of primary brain tumors); distamycins (antibiotics); and aphidicolin (an antiviral antibiotic produced by Cephalosporium aphidicola and other fungi).
Common fragile sites do not appear to be associated with any disease. In contrast, rare fragile sites are all associated with disease conditions. Although most rare fragile sites have been studied mostly in humans, they have also been described in a wide variety of mammals. In total, 21 human fragile sites have been molecularly characterized: eight rare fragile sites and 13 common human fragile sites. Since their discovery, fragile sites have been implicated in constitutional and cancer chromosome rearrangements and recent studies suggest that fragile sites may serve as markers of chromosome damage during early tumor formation.
Fragile sites are thought to genetically predispose humans to develop certain tumors has been shown to be increased in Boxer dogs with mast cell tumor.
Adapted from:
1. Chromosomes: Organization and Function. Adrian T. Sumner
2. Bromodeoxyuridine induces chromosomal fragile sites in the canine genome. Stone DM, Stephens KE.
3. Common fragile sites as targets for chromosome rearrangements. Martin F. Arlta, Sandra G. Durkina, Ryan L. Raglanda and Thomas W. Glover
4. Small Animal Clinical Oncology. Stephen J. Withrow, E. Gregory MacEwen
Go Pets America recommends seeking the advice of your local veterinarian for the most appropriate vaccination program and for the diagnosis and treatment of your pet's health problems. For vaccination requirements please contact your state and local licensing authorities.
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