**4.2 Chromosome**

Chromosomal changes are found in a few *de novo* chordomas having poorer prognosis and most common genomic alterations are observed in chromosome numbers 1p, 3, 4, 9, 10, 13, and 14 [11]. It was found that chromosomal gain is less common than chromosomal deletion. Bai and his colleagues have identified

**Figure 1.** *A schematic presentation of notochord remnant and Chordoma [9].*


*Challenges in Diagnosing Chordoma (Skull Base Tumors) DOI: http://dx.doi.org/10.5772/intechopen.102048*


#### **Table 1.**

*Different pathways and cyto-molecular factors associated with the pathogenesis of Chordoma [11, 13, 14].*

germline duplication of the TBXT gene that encodes brachyury, a transcription factor that plays an important role in familial Chordoma [12]. A common genetic polymorphism in *TBXT* is consequently associated with an increased risk for both sporadic and familial chordoma. They have found that *PBRM1, B2M* and *MAP3K4*

are the most frequently mutated cancer driver genes in chordoma. Given the role of *PBRM1* and *SETD2* in chromatin remodeling, it can be proposed that epigenetic dysregulation may play a vital role in chordoma development. Bai and his group suggested that amplifications of *TBXT* gene, homozygous deletion of *CDKN2A* and mutations in genes like *PBRM1, SETD2, ARID1A* etc. are the most common genomic events in sacral Chordoma [12].
