Though other hypotheses for HD pathology can explain different subsets of these observations, our hypothesis is the only one (Zuccato et al., 2003; Cornett et al., 2005; Atwal et al., 2007; Nalavade et al., 2013; Yano et al., 2014) that, to our knowledge, is consistent with the experimentally-observed dependence of proper Htt targeting on the presence of the N17, poly-glutamine, and poly-proline sequence motifs. This evidence concerns the gene HTT and Huntington disease.