Objective: To delineate the clinical and genetic profiles of dystonia patients with SGCE mutations in the Chinese population.

Background: SGCE mutations are the primary cause of myoclonus-dystonia syndrome, which is characterized by a combination of myoclonic jerks, dystonic postures, and psychiatric symptoms. Its genetic and phenotypic characteristics in the Chinese population remain largely unknown.

Method: SGCE mutations were screened using whole-exome sequencings (WES) in a cohort of dystonia patients from two movement disorder centers in mainland China. In addition, we conducted a review of the clinical and genetic features of dystonia patients carrying SGCE mutations in the Chinese population.

Results: A total of 214 patients (108 males and 106 females) diagnosed with dystonia were included in this study. The average age at onset was 23.7 ± 14.3 years (range from 1 to 65 years). Four SGCE variants were detected in five patients, including two spicing variants (c.110-2A>G and c.109+5G>C), one nonsense variant (c.304C>T), and one missense variant (c.1282G>A). Among these variants, c.110-2A>G and c.304C>T were classified as likely pathogenic/pathogenic variants, while c.109+5G>C and c.1282G>A were classified as variants of uncertain significance (VUS). Among these five patients, four presented with myoclonus-dystonia syndrome, and one patient presented with isolated segmental dystonia. None of these patients showed symptoms of psychiatric disorders. In the review of previous literature, 35 cases from 15 pedigrees reported in the Chinese population were enrolled. The average age at onset was 12.1 ± 9.2 years (data available for 30 patients). Dystonia was observed in 27 patients, while myoclonus was present in 28 patients. Seven patients were reported to have psychiatric symptoms, including anxiety, obsessive-compulsive disorder, panic, depression, neurosis, and alcohol dependence. Regarding the genotype, fifteen pathogenic variants were detected, including two spicing mutations (c.662+1insG and c.1037+1G>A), seven frameshift mutations (c.842delA, c.524_531del TGGCCAGT, c.835_839delACAAA, c.987_993insGGTCCTT, c.289delC, c.380delC and c.1011delA), four nonsense mutations (c.709C>T, c.1011T>A, c.1114C>T and c.856C>T), and two large segment deletions (c.exon2-11del and c.exon5del).

Conclusion: Our study expands the genetic spectrum and clinical profiles of patients with SGCE mutations.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/sgce-mutations-in-chinese-dystonia-patients-a-dual-center-sequencing-study-and-literature-review/