PBRM1 mutations were present in 8.3% (n =  9/116) of chordoma NOS cases and 7.1% (n =  1/14) of conventional chordoma, while ARID1A mutations appeared in 6.4% (n =  7/116) of chordoma NOS cases and 14.3% (n =  2/14) of conventional chordoma. This evidence concerns the gene ARID1A and chordoma.