The importance of using absolute mutant frequencies to compare mutation spectra

Because damage to the cellular DNA is very hazardous for a cell, it is impo rtant to identify compounds, which can cause DNA damage. To investigate the mutagenic effect of a particular agent of interest, usually mutation spect ra are determined in a selected target gene. The most commonly used method to compare different mutation spectra with each other, is the comparison of the percentages of each type of mutation. In this paper, it is emphasized that comparison of percentages can lead to incorrect conclusions and theref ore another determinant, the absolute mutant frequency, should be used. (C) 2001 Elsevier Science B.V. All rights reserved.