A comparison of purine and pyrimidine pools in Bloom's syndrome and normal cells.

Nucleotide content of normal and Bloom's syndrome fibroblasts and lymphocytes were examined by reversed phase HPLC. The ATP/ADP ratio in primary cultures of normal human fibroblasts was at least three fold higher than in the primary cultures of Bloom's syndrome fibroblasts. After three months in culture the ratios of ATP/ADP of the Bloom's cells approach those of normal fibroblasts. Individual nucleotide measurements showed that initial differences did not reflect excess ADP, but rather very low levels of ATP in Bloom's syndrome fibroblasts. The amount of ATP increased gradually during culture. However, even after three months in culture, significant differences were noted in ATP levels between Bloom's syndrome fibroblasts and normal fibroblasts. Thus a defect in Bloom's syndrome is correlated with a defect in purine biosynthesis or ATP generation.