DYT1 dystonia is a hereditary neurological movement disorder characterized by uncontrollable muscle contractions. It is caused by a heterozygous mutation in Torsin A ( TOR1A ), a gene encoding a membrane-embedded ATPase. While animal models provide insights into disease mechanisms, significant species-dependent differences exist since animals with the identical heterozygous mutation fail to show pathology. Here, we model DYT1 by using human patient-specific cholinergic motor neurons (MNs) that are generated through either direct conversion of patients’ skin fibroblasts or differentiation of induced pluripotent stem cells (iPSCs). These human MNs with the heterozygous TOR1A mutation show reduced neurite length and branches, markedly thickened nuclear lamina, disrupted nuclear morphology, and impaired nucleocytoplasmic transport of mRNAs and proteins, whereas they lack the perinuclear “blebs” that are often observed in animal models. Furthermore, we uncover that the nuclear lamina protein LMNB1 is upregulate...