In poorly differentiated and anaplastic thyroid carcinoma, RAS-like and BRAF V600E-like signatures are partially retained since a subset of cases is characterized by mutations of BRAF and RAS genes at prevalence rates not very different from those of well-differentiated papillary and follicular carcinoma. The gene discussed is BRAF; the disease is thyroid gland undifferentiated (anaplastic) carcinoma.