HTT and Huntington disease: Figure 1 shows the general appearance of in vitro cultures of dermal fibroblasts obtained from the HD patient and the donor, who had no neuronal pathology. Huntingtin showed a diffuse distribution through the cytoplasm without forming visible aggregates in both of the fibroblast populations (Fig. 2). However, a substantial difference was observed in striatal neurons derived from these fibroblasts. Huntingtin was still diffusely distributed through the cytoplasm and formed no visible aggregates in neurons derived from DF1 fibroblasts (Fig. 3).