Current information on the nature and incidence of somatic mutations other than BRAF in HCLc is based on limited data—namely, whole-exome sequencing (WES) of 9 cases [9,49,50] and targeted sequencing using a large panel of cancer-related genes in 73 cases [11,26,42], together with targeted sequencing of specific genes: CDKN1B, MAP2K1, and KLF2. Here, MAP2K1 is linked to cancer.