Cyclin A2 (CCNA2) was identified a target gene of miR-124, and increased miR-124 expression in R6/2 mice altered CCNA2 expression and the proportion of cells in S phase in the HD cell model, indicating that downregulation of miR-124 expression increased CCNA2 expression in HD and was involved in deregulation of the cell cycle in STHdh (Q111)/Hdh (Q111) cells (Das et al., 2013). Here, CCNA2 is linked to Huntington disease.