ALK and thyroid cancer: In addition to common gene mutations, such as mutations in BRAF [7–11], matrix metalloproteinase-2 [12], Ras family genes [13, 14], phosphatase and tensin homolog (PTEN) [15, 16], phosphatidylinositol 3-kinase (PIK3CA) [17, 18], anaplastic lymphoma kinase (ALK) [19], β-catenin 1 (CTNNB1) [20, 21], isocitrate dehydrogenase 1 (IDH1) [22], survivin [23], and epidermal growth factor receptor (EGFR) [24, 25], epigenetic alterations have also been shown to be important in thyroid cancer.