The accumulation of mutant HTT aggregates in the brain is a hallmark of the HD neuropathological process.7 To validate on-target silencing efficiency of the AAV5-miHTT-155 and AAV5-miSNP67T-155 expression products, we performed IHC using an anti-HTT antibody that binds to the mutant HTT (Figure 2c). Here, HTT is linked to Huntington disease.