Objective: In the present work, we describe the case of a 54 years old man who presented a young-age onset (7-8 years old) of unilateral tremor of the right hand, spreading to contralateral during the following 4-5 years and worsening during adult life, with abnormal and painful muscular contractions of both hands.

Background: DYT1 gene mutations lead to early-onset dystonia that typically begins with twisting of an arm or leg and subsequent generalization. Anyway, it has emerged that the phenotype associated with the DYT1 mutation can be somewhat variable.

Method: Clinical and neurophysiological evaluations were performed at our center. Previously conducted neuroimaging studies were negative for pathological findings.

Results: The patient had an unremarkable history for perinatal or central nervous system insults. Family history revealed similar symptoms in the patient’s father and father’s uncle with juvenile onset. At age of 43 he first came for evaluation at our Institute, where for suspected dystonic tremor was initially started therapy with anticholinergic drugs and botulinum toxin injections, with mild clinical benefit. At subsequent clinical re-evaluation, brief and sudden jerks appeared at right upper limb; at electromyographic recording of arms muscles, short jerks (duration range 50 to 200 ms) occurring at rest and during posture with pseudo-rhythmic pattern were found in the distal right arm, with co-contraction and alternating contractions of antagonist muscles. Clinical and familiar history, associated with neurological findings and neurophysiological examination, were suggestive for myoclonic dystonia, suspected DYT11 gene mutation. Genetic counseling and NGS complete molecular analysis of genes associated with isolated/combined dystonia were performed.

Conclusion: Recurrent deletion c.907_909del (p.Glu303del) of TOR1A gene was detected. Thus, we concluded for an atypical presentation of DYT1 dystonia with segmental dystonia and myoclonus. Clonazepam was initiated with great clinical benefit.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/dyt1-gene-mutation-an-atypical-presentation-with-myoclonic-dystonia/