Mutations of CDKN2A, SWI/SNF (switch/sucrose non-fermentable) chromatin remodeling complex genes (ARID1A, ARID1B, ARID2, ARID5B, SMARCB1, PBRM1, ATRX), histone methyltransferase genes (KMT2A, KMT2C, KMT2D, SETD2), and DNA mismatch repair (MMR) genes (MSH2, MSH6, and MLH1) are associated more frequently with anaplastic thyroid carcinoma as opposed to other aggressive forms of thyroid cancer [19, 28]. The gene discussed is CDKN2A; the disease is thyroid gland undifferentiated (anaplastic) carcinoma.