Notably, the mutation frequencies differ from those seen in follicular cell-derived tumors, with HRAS being the most frequently mutated gene (∼25% of MTC), followed by KRAS (∼15% of MTC), while NRAS mutations are very uncommon (less than 5%) (39, 40, 41). The gene discussed is KRAS; the disease is medullary thyroid gland carcinoma.