Clinical Phenotype Comparison in Polish Patient Cohorts with and Without Molecular Diagnosis of Dystonia

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Abstract
Background: Dystonia is a heterogeneous hyperkinetic movement disorder characterized by sustained or intermittent muscle contractions causing abnormal movements and postures. Although numerous genes associated with dystonia have been identified, the genetic background remains unknown in many patients. Data on genotype–phenotype correlations in Polish populations remain limited. Objective: To analyze the clinical characteristics of patients with generalized dystonia and compare clinical features between individuals with and without genetically confirmed dystonia-causative variants in a Polish cohort. Methods: A retrospective analysis of patients diagnosed with generalized dystonia at a single neurological center was performed. Diagnosis was established according to MDS criteria. Genetic analysis included whole-exome sequencing, targeted NGS genetic panel, MLPA, Sanger sequencing and PCR_RFLP analysis. Clinical and demographic data were extracted from medical records. Clinical characteristics of individuals with and without causative variants were compared. Results: A total of 113 patients with generalized dystonia were included. Genetic variants were identified in 13 patients (11.5%). These included variants within the TOR1A, THAP1, SGCE, GCH1, NKX2-1, SLC2A1, KMT2B, PDHA1, MFN2, and GNAL genes. We found detailed clinical data of 46 patients included in the study. Our comparative analysis of patients with causative (n = 7) and without causative variants (n = 39) revealed no statistically significant differences in age of onset, initial symptom localization, treatment response, family history, or associated neurological features. Conclusions: In this cohort of Polish patients with generalized dystonia, we identified pathogenic variants in approximately 11.5% of cases. No significant clinical differences were observed between patients with genetically confirmed dystonia and those without identified variants. In this study, we report the first two Polish cases with DYT-GNAL variants. Further studies are required to reveal the clinical heterogeneity of dystonia and characterize dystonia subtypes.

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