Sensitivity of Bloom's syndrome lymphocytes to ethyl methanesulfonate.

Ethyl methanesulfonate induced several times as many sister chromatid exchanges (SCE's) in lymphocytes from individuals affected with Bloom's syndrome as in lymphocytes from controls or heterozygotes. In cultures of cells from an individual with Bloom's syndrome who had two populations of lymphocytes circulating in his blood--'low' cells having normal spontaneous frequencies of SCE's and 'high' cells having elevated frequencies--only the high cells showed the increased sensitivity to ethyl methanesulfonate.