Purine, Thymidylate and Amino Acid Requirements for Human Lymphocyte Transformation and Fragile Chromosome Site Expression
Observations of heritable fragile site expression on human chromosomes being dependent on the type of tissue culture medium1,2 have provided a basis for investigating the metabolic aspects of fragile site expression. Fragile sites are non-staining gaps of variable width usually involving both chromatids. The sites are inherited in a Mendelian dominant manner and except for fragile site Xq27, which is associated with X-linked mental retardation, the rest of the fragile sites have not been associated with any phenotypic abnormality. Restriction of folic acid was found to be required for the expression of all but one fragile site. The expression of heritable fragile site 10g25 requires bromodeoxyuridine (BUdR) in medium deficient in folic acid and thymidine3. Recently, the frequency of fragile site Xq27 was found to be increased by 5-fluorodeoxyuridine (FUdR)4, a potent inhibitor of thymidylate synthetase.
KeywordsFragile Site Dermatitis Herpetiformis Amino Acid Requirement Site Expression Deficient Medium
Unable to display preview. Download preview PDF.