HTT and juvenile Huntington disease: To test whether any evidence of pre-miRNA competition effects can be detected in experimental data, we next investigated the characteristics of miRNA sequences from the YAC128 mouse model of Huntington’s disease where Dicer1 mRNA expression levels in the YAC128 mice (expressing transgenic human HTT with 100−120 glutamine repeats) have been reported to be reduced by half compared with WT mice (which express native mouse Htt only) (figure 4d), while mRNA expression levels of proteins in the pri-miRNA processing machinery or pre-miRNA export were unaffected [31].