Objective: To create a resource of induced pluripotent stem cells (iPSCs) as models for exploring mechanisms of pathogenesis in DYT1 dystonia.

Background: DYT1 an autosomal dominant early-onset movement disorder characterized by involuntary muscle contractions which force body parts into abnormal postures and or movements. DYT1 is caused by a 3-base-pair deletion (GAG mutation) in the Torsin1A gene. The function of the Torsin1A protein is only partially understood, but many studies point to a problem with dopaminergic neuron function.

Methods: Fibroblasts from 3 healthy controls and 3 DYT1 patients(with GAG mutations in Torsin1A) were reprogrammed to iPSCs. Two independent lines were created for each case. Immunocytochemistry was performed on iPSCs to confirm expression of pluripotency markers. We nest confirmed the karyotype of the iPSCs. Pluripotency was verified by testing ability to differentiate to the three germ layers: ectoderm, mesoderm, and endoderm. Gene expression and protein composition profiles were then determined for iPSCs from cases and controls.

Results: All 12 lines had immunostaining profiles consistent with pluripotency, and possessed the ability to differentiate into all 3 germ layers. All lines had normal karyotypes. All lines expressed high levels of genes typical of pluripotent cells. RNA-Seq identified a total of 81 differentially expressed genes between DYT1 and healthy controls with nominal p<0.001. After correcting for multiple comparisons, none of the genes remained significantly differentially expressed at a FDR<0.1. Studies addressing protein expression profiles and metabolic abnormalities are underway, as well as studies addressing their ability to differentiate into neurons.

Conclusions: We have validated multiple iPSC lines from patients with LND and matched controls. The lines from patients show consistent abnormalities in gene expression profiles and are being used now to evaluate dopamine neuron function.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/disease-modeling-of-dyt1-using-patient-induced-pluripotent-stem-cells/