WWTR1 and cancer: YAP1 amplification and minor gene alterations in Hippo components. TCGA includes a comprehensive landscape of somatic genetic alterations in HNSCC, with the second highest incidence of YAP1 gene amplification (4.4% of the cases) and the third highest incidence of WWTR1 (TAZ) gene amplification (8.8%) among all cancers [51].