HTT and Huntington disease: Although our evaluation of 16 precandidate pri-amiRNAs in 3 human cell lines (HeLa, U251MG, and neuronally differentiated SH-SY5Y cells) for lowering of endogenous HTT mRNA revealed substantial differences between the pri-amiRNAs, the rank order in vitro with respect to target lowering did not completely predict the rank order for target lowering in vivo in the striatum, an HD-relevant brain region.