Clinical characteristics of THAP1 related dystonia: a case report with phenotypic review.

Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions resulting in abnormal movements and postures. DYT-THAP1 is one of the most frequent genetic causes of generalized dystonia and may present with characteristic clinical features that help guide diagnostic suspicion before molecular confirmation. We report a 58-year-old man who developed dysphagia and dysarthria at 22 years of age, followed by progressive dystonic posturing involving the upper limbs, face, neck, and lower limbs. Family history revealed a similar condition in his father. Neurological examination demonstrated generalized dystonia with marked cranio-cervical and bulbar involvement. Brain magnetic resonance imaging and extensive metabolic and autoimmune investigations were unremarkable. Given the clinical presentation and family history, a genetic etiology was suspected. A dystonia gene panel identified a variant in the THAP1 gene, NM_018105.3:c.108G > T (p.Trp36Cys), establishing the diagnosis. Cranio-cervical involvement and prominent bulbar symptoms may represent important clinical clues suggesting DYT-THAP1 in patients with generalized dystonia, highlighting the importance of careful phenotypic characterization.