Clinical phenotype heterogeneity in a family with ε-sarcoglycan gene mutation

Abstract

Aim of the study. This paper describes six cases of patients with myoclonus-dystonia syndrome who are members of a family in which an SGCE gene mutation has been confirmed.Clinical rationale for the study. Myoclonus-dystonia syndrome is a very rare disease, with an incidence in Europe of about 2 in every million. Due to the fact that only a few case reports of this illness are accessible in the literature, the material we collected seems to be valuable for clinical practice. Materials and methods.A history was taken, and physical and genetic examinations of the patients were performed. Furthermore, the clinical examination of three patients was video-recorded.Results. The clinical picture of the disease varied significantly between the described individuals, from a healthy carrier of the SGCE mutation to patients presenting mild to moderate symptoms. The differences concerned the age at onset of the disease, the initial symptoms, the intensity of involuntary movements, and the predominant symptoms. In addition to the typical movement disorders which are myoclonus and dystonia, in the described family there was also the coexistence of epilepsy, obsessive-compulsive behaviour, dyslexia, dysgraphia, non-harmonious development of cognitive processes, as well as mild phenotypic features of muscular dystrophy. The mutation (NM_001099401.2:c.806-809delACTG) found in the presented family has not been described elsewhere. Conclusions and clinical implications.Our description of six cases of patients demonstrates the heterogeneity of the natural course of the disease, even in patients with the same mutation. It seems reasonable to regularly examine relatives of patients with myoclonus-dystonia syndrome, who should be observed for involuntary movements as well as non-motor symptoms.

Myoclonus-dystonia (DYT11, DYT-SGCE) — a channelopathy?

“…Neuropsychological evaluation revealed pronounced fatigability, reduced working memory, difficulty in concentrating, increased sensibility to stress, marked anxiety, and depressive symptoms. When tested at age 36, the patient made mistakes in alphabetical ordering, which might indicate similar learning deficits as in the Polish family [1]. A sibling had myoclonus since the age of six, cervical and arm/hand dystonia, and developed anxiety and depression.…”

“…In this edition of the Polish Journal of Neurology and Neurosurgery, Dr. Kaczyńska et al report the case of a Polish family with myoclonus-dystonia (M-D) and a novel truncating mutation in the gene for epsilon-sarcoglycan (SGCE) [1]. Six members of the family were affected by upper-body-predominant myoclonic jerks, dystonia, and/or tremor, such as classically characterise this disorder [2,3].…”