By quantifying the number and proportion of MAP2+ and TAU+ cells (as defined by DAPI) we found that the Huntington's disease fibroblasts converted into induced neurons 4 weeks post-transduction with a similar purity (number of induced neurons / number of DAPI cells) and conversion efficiency (number of induced neurons / number of starting fibroblasts) (Fig. 1C and Supplementary Fig. 1C and D) as to that seen with control fibroblasts. Here, MAP2 is linked to Huntington disease.