HTT and Huntington disease: In addition to the HTT gene, several genetic modifiers encoding proteins that are associated with HD through different mechanisms have been identified recently, such as Nme1 (suppressing) mutant HTT),[185] NF (providing) neurotrophic support,[186] CYP46A1 (affecting brain cholesterol metabolism),[187] and TLR4/TREM2 (affecting inflammation).[188] Targeting these genes via gene therapy led to decreased HTT aggregation and improved motor performance in HD animal models, which could be potential therapeutic targets for HD drug development.[185, 186, 187, 188]