HAP1 and Huntington disease: In patients with the M441T mutation inthe gene encoding the Htt-associated protein (Hap1), HD manifested itself at anearlier age due to a weakened interaction between Hap1 and mHtt and, thereby,increased Htt-mediated toxicity [23].Recently, a single nucleotide polymorphism in the NF-κB binding sitelocated in the Htt gene promoter was shown to reduce thepromoter activity and, as a consequence, Htt expression, which led to latemanifestations of HD [24].