PTCH1 and skin basal cell carcinoma: The analysis of the mutational status according to patients and tumour characteristics revealed that PTCH1 mutations were significantly associated with intermittent sun exposure (p = 0.046), and with the occurrence of single BCC lesions (p = 0.021), and NOTCH1 mutations were more frequent in BCCs arising on the trunk compared to the head/neck and extremities (p = 0.001).