In addition, calpain-derived fragments have been observed both in mouse models expressing human huntingtin with 150 polyQ (Gafni et al., 2004; Landles et al., 2010), and in post-mortem caudate samples from HD patients which also presented increased calpain levels (Gafni and Ellerby, 2002; Gafni et al., 2004). This evidence concerns the gene HTT and Huntington disease.