One month after injection, western blotting analysis of the injected brain tissues demonstrated that the cytoplasmic TDP‐43 expression increased the level of N‐terminal Htt at 55 kDa and 70 kDa (Figure 2b,c), which is equivalent to mutant exon1 Htt in HD KI mouse brain and can be recognized by Htt EM48 and polyQ 1C2 antibodies (Figure 2d) (Yang et al., 2020). This evidence concerns the gene HTT and Huntington disease.