These results not only validate the evolutionary direction of FCs by the SKY-based NJ tree, but also identify a precursor (SVZR-FC0) of the cNRT2N-1×-bearing FC1, SVZR-FC1, which harbors a cancer driver alteration: a specific homozygous deletion at Nf1 tumor suppressor gene (Fig. 5d). The gene discussed is NF1; the disease is cancer.