Psychiatric symptoms in myoclonus-dystonia syndrome are just concomitant features regardless of the SGCE gene mutation

Introduction: Among myoclonus-dystonia syndrome (MD) patients, psychiatric disorders including depression, anxiety, alcohol dependence, obsessive-compulsive disorder (OCD) and panic disorder have been frequently reported to be related with the epsilon-sarcoglycan gene (SGCE) mutation. However, the rate of psychiatric disorders has not been compared between MD patients with the SGCE mutation (SGCE (+)) and without the SGCE mutation (SGCE (-)). We analyzed the psychiatric data in both SGCE (+) and SGCE (-) MD patients to determine the association of the SGCE mutation with psychiatric disorders in MD.

Methods: Twenty-six MD patients who fulfilled the Grunewald's criteria and underwent a SGCE gene study were enrolled. Patients were divided into two groups according to their SGCE status (SGCE (+) and SGCE (-) group). They were systematically assessed using a standardized protocol including motor severity scales and psychiatric questionnaires for depression, anxiety, alcohol dependence, OCD and panic disorder.

Results: Fifteen SGCE (+) and eleven SGCE (-) patients were enrolled. Mean age at onset, disease duration, family history, alcohol responsiveness and motor severity were not different between the SGCE (+) and SGCE (-) group. Although more than half (53.8%) of all the MD patients had psychiatric symptoms, there were no significant differences between the SGCE (+) and SGCE (-) group in terms of their psychiatric questionnaire scores and rate of psychiatric disorders.

Conclusions: Psychiatric features are not likely to be related with the SGCE mutation itself but just bespeak disability in clinical MD syndrome regardless of the SGCE mutation.