HTT and Huntington disease: Although not clear yet, one of the possible factors that may lead to such a differential disease stage-dependent decrease of ganglioside levels, may be related to the effect on mutant Htt on the regulation of gene expression and/or activity of enzymes involved in the synthesis and degradation of each ganglioside, already reported in both HD animal models and human patients (Desplats et al., 2007; Maglione et al., 2010; Denny et al., 2010).