TOR1A and early-onset generalized limb-onset dystonia: DYT1 dystonia is caused by a mutation in the TOR1A gene (c.904_906delGAG/907_909delGAG; p.Glu302del/Glu303del; TOR1AΔE), which encodes the protein torsinA; this mutation results in an in-frame deletion of a codon for glutamic acid (ΔE-torsinA) [28, 29].