KRAS and melanoma: The mutation frequency of KRAS was also significantly enriched relative to the frequency of extracranial melanoma metastases; 8% (4/50) in our dataset vs 2.1% (6/274) in extracranial melanoma metastases in SKCM-TCGA (p = 0.0413, logistic regression Wald t test, see Supplementary Methods).