The CV78 filter was calibrated to remove all non-specific variants. It removed all low-frequency variants, irrespective of whether they were a genuine mutation or an error. As a result, a few of the somatic mutations detected in tumor tissues were also removed by the CV78 filter. Thus, the current filter thresholds might be too stringent, and there is some room for improvement. A different approach for evaluating whether a variant is a mutation or an error would involve referencing normal DNA sequences deposited in in-house databases [5, 23]. The integrated digital error suppression (iDES) technique includes such a bioinformatic step . Since iDES is not based on previous knowledge of tumor-specific mutations, it is suitable for exploratory studies. Although the iDES identifies errors due to DNA damage to some extent, it by itself, cannot remove mutations present in normal cells.