Clinical and Genetic Spectrum of ANO3-Related Dystonia with Treatment Responses in a Chinese Cohort

Background: Variants in anoctamin 3 (ANO3) are linked to autosomal dominant dystonia, commonly known as DYT-ANO3 (OMIM: #615034). While craniocervical dystonia constitutes the most frequently observed phenotype, its clinical manifestations display significant heterogeneity. Nevertheless, the data concerning the genetic characteristics, clinical features, and therapeutic outcomes of ANO3-related dystonia within Asian populations remain scarce. Methods: Whole-exome sequencing was conducted on 661 Chinese patients, comprising 356 individuals with dystonia and 305 individuals with non-dystonic movement disorders who served as an internal disease–control cohort. Candidate ANO3 variants were evaluated based on population frequency, predicted deleteriousness, ACMG criteria, and aggregate frequency analyses. A retrospective review was performed of clinical features and treatment responses. Results: Fifteen rare ANO3 missense variants were identified in 16 patients with dystonia and one non-dystonic individual, including one pathogenic variant, six likely pathogenic variants, and nine previously unreported variants. The rare ANO3 variants were significantly enriched in the dystonia cohort compared with the controls. ANO3-related dystonia exhibited broad clinical heterogeneity, with frequent cervical involvement (62.5%) and tremulous features (75%), and occasionally extended beyond classical isolated dystonia. Oral medication and botulinum toxin showed variable benefit, whereas deep brain stimulation was associated with marked improvement in selected medically refractory patients. Conclusions: This study broadens the genetic and clinical spectrum of ANO3-related movement disorders in a Chinese cohort. The findings support substantial clinical heterogeneity in DYT-ANO3 and suggest that deep brain stimulation, especially STN-DBS, may be considered in selected refractory cases, although further studies are needed.