Fig. 6

Continuous monitoring of the QC material using Levey-Jennings plots. The lowest frequency of a SNV (a) and of a small DEL (b) from the 8 variants detected in the QC material listed in Table 7 were monitored on each run over a period of 6 months using Levey-Jennings plots. The plots show the expected mean value, previously assessed by 10 independent runs, as well as expected limits: two standard deviations (SD) (hatched lines), and three SD (solid lines). All variants frequencies are within three standard deviations of the mean expected value