Fig. 4
Parameters of the second derivative plots of ALK fusion variants. Some key points are marked as a, b, e (zero point) and c, d, f (local peak point). All ALK fusion variant amplicons were divided into monotonically increasing (a) and non-monotonic (b) at the interval [b, d] of second derivative plots. The negative derivative plot (black line) and the second derivative plot (grey line) of variant E13:A20 (a) and variant E6a/b:A20 (b) are shown. The interpeak temperature difference (∆Tm) (interval [a, e]), peak temperature span (PTS) (interval [d, f]) and the peak height ratio (H1/H2) were used as parameters for monotonically increasing melting plots. ∆Tm, inner temperature span (ITS) (interval [a, c]) and H1/H2 were used as parameters for non-monotonic melting plots
