PTCH1 and skin basal cell carcinoma: Chromosome 9q includes the tumor suppressor PTCH1, the most crucial driver gene for BCC, and a cluster of 3 miRNA genes (MIRLET7A, MIRLET7B, and MIRLET7F), members of the tumor suppressor let-7 family [56], whereas chromosome 9p includes the CD274 (encoding PD-L1), CD273 (encoding PD-L2), and JAK2 oncogenes.