These mutations affect various subunits of the SWI/SNF chromatin remodeling complex, with ARID1A being the most frequently mutated gene, followed by SMARCA4, ARID1B, ARID2, PBRM1, and SMARCB1 [27,28], mutations we have found to be common in adult chordoma. This evidence concerns the gene ARID1A and chordoma.