Ultraviolet light sensitivity and delayed DNA-chain maturation in Bloom's syndrome fibroblasts


BLOOM'S syndrome (BS) is a rare, autosomal recessive condition of pre-natal and post-natal growth retardation, sun-induced telangiectatic erythema, impaired immunological function and predisposition to cancer1,2. BS cells show a high incidence of chromosome breakage and rearrangement often with abnormal nuclear morphology. Chromosome exchanges appear mainly to involve homologous chromosomes, while sister chromatid exchanges are abnormally frequent3. These features suggest a defect of DNA replication or repair. In particular, the high incidence of sister chromatid exchanges may be explained if free ends in the DNA, resulting from abnormalities of DNA synthesis and/or repair, act as initiation points for exchange4. We report here that BS fibroblasts are abnormally sensitive to ultraviolet irradiation in vitro and show a rate of DNA synthesis and DNA chain maturation lower than controls. They do not, however, have defective bypass of ultraviolet light-induced lesions during DNA replication as xeroderma pigmentosum (XP) variants5.

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GIANNELLI, F., BENSON, P., PAWSEY, S. et al. Ultraviolet light sensitivity and delayed DNA-chain maturation in Bloom's syndrome fibroblasts. Nature 265, 466–469 (1977). https://doi.org/10.1038/265466a0

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