Also, reduction of HTT-interacting proteins involved in endocytosis might impair endocytic and intracellular trafficking in HD (Kalchman et al., 1997; Li et al., 1998; Sittler et al., 1998; Modregger et al., 2002; Singaraja et al., 2002; Trushina et al., 2004). The gene discussed is HTT; the disease is Huntington disease.