Molecular genetic studies first identified the SS [9] locus on chromosome 2q37.3 and nonsense mutations in the gene that codes for the TWIST2 bHLH transcription factor, i.e., c.486C > T (p.Gln119*) and c.324C > T (p.Gln65*), in Puerto Rican (PR) and Omani SS patients, respectively. Here, TWIST2 is linked to synovial sarcoma.