CDKN2A and chordoma: The molecular characterization of these tumors has been well delineated; nearly all chordomas express T-brachyury (Miettinen et al. 2015), approximately 80% of chordomas have loss of CDKN2A, 16% have PI3K mutations, 17% have SWI/SNF mutations (poorly differentiated and some de-differentiated chordomas), and 10% have LYST mutations (Le et al. 2011; Tarpey et al. 2017).