MYOD1 and Huntington disease: To this end, we generated from the MyoD line an isogenic MyoD iPSC line expressing HTTEx1Q72-mCherry (Supplementary Figure 2A), and sought to identify the presence of HD-specific pathological alterations in myotubes in the following neuronal/myotube co-culture combinations: (1) Neu ctr /Myo ctr [no expression of the pathogenic HTTEx1Q72 (Ctr)]; (2) Neu ctr/Myo HTTEx1Q72-mCherry [cell-autonomous (CA)]; (3) Neu HTTEx1Q72-mCherry/Myo ctr [transmission (T)]; and (4) Neu HTTEx1Q72-mCherry/Myo HTTEx1Q72-mCherry (T+CA).