Novel Phenotypes and Deep Intronic Variant Expand TH-Associated Dopa-Responsive Dystonia Spectrum

Approximately 20% of dopa-responsive dystonia (DRD) cases remain genetically unresolved. Using whole-genome sequencing, we identified two TH variants in a young DRD patient, including a novel deep intronic variant. Minigene assays confirmed that this variant causes aberrant splicing. The patient exhibited an atypical disease progression compared with typical TH-associated DRD cases, presenting with generalized dystonia, episodic hypotonia, Parkinsonism, and oromandibular dyskinesias. These findings, including the first known documented deep intronic TH variant, expand our understanding of TH-associated DRD's phenotypic and genotypic spectrum, aiding clinical evaluation.