MRC1 and metastatic neoplasm: Testing of the NRAS gene was only ever done in combination with KRAS. Altogether, including results obtained from either primary or metastatic tumour, the rate of mutation was: 45.6% for KRAS (n = 52), 3.5% for NRAS (n = 3), 13.6% for BRAF (n = 6), 13.3% for PIK3CA (n = 2) and 14.3% for MMR (n = 3).