While overall upregulation of cell-cycle gene expression is observed between NPC and astrocyte stages in HD samples, as seen with Cyclin D1 (Additional file 1: Figure S7g), a small number of DE genes, such as Cyclin D2 (Additional file 1: Figure S7h), show reduced expression compared to WT cells across differentiation. This evidence concerns the gene CCND1 and Huntington disease.