PD-1 was expressed by the highest percentage of T-cells in malignant PC lesions and was significantly different compared to control prostates (median 71.0% vs. 41.5%, p = 0.005) and BPH tissue (median 71.0% vs. 34.6%, p < 0.001) (Figure 4A). The gene discussed is PDCD1; the disease is pachyonychia congenita.