TOR1A and Dystonia: Thus, the missense polymorphism Asp216His (rs1801968) in the TOR1A (DYT1) gene serves to moderate the clinical impact, in both cis and in trans, of the TOR1A c.904-906 del GAG mutation, the major mutation underlying early-onset dystonia (Kock et al. 2006; Risch et al. 2007; Martino et al. 2013).