Progressive myoclonic epilepsy type 1: Report of an Emirati family and literature review

PURPOSE: Progressive myoclonic epilepsy type one is a neurodegenerative disorder characterized by action- and stimulus-sensitive myoclonus, tonic–clonic seizures, progressive cerebellar ataxia, preserved cognition, and poor outcome. The authors report clinical, neurophysiological, radiological, and genetic findings of an Emirati family with five affected siblings and review the literature. METHODS: All data concerning familial and clinical history, neurologic examination, laboratory tests, electroencephalogram, brain imaging, and DNA analysis were examined. RESULTS: Genetic testing confirmed the diagnosis of autosomal recessive progressive myoclonic epilepsy type 1 (EPM1) in two males and three females. The median age at onset was three years. Action- or stimulus-sensitive myoclonus and generalized seizures were recorded in 100% of our patients, at median age at onset of 3 and 4 years, respectively. Multisegmental myoclonus and generalized status myoclonicus were observed in 80% of our patients. Dysarthria and ataxia developed in 100% of our patients. Vitamin D deficiency and recurrent viral infections were noticed in 100% of our cohort. Cognitive, learning, and motor dysfunctions were involved in 100% of our patients. The sphincters were affected in 60% of our patients. Abnormal EEG was recorded in 100% of our cohort. Generalized brain atrophy progressively occurred in 60% of our patients. Phenytoin and carbamazepine were used in 60% of our patients with worsening effect. Valproate and levetiracetam were used in 100% of our patients with improving effect. CONCLUSIONS: This is the first to report a family with EPM1 in UAE. Our study emphasized a particular phenotype expressed as earlier disease onset, severe myoclonus, and generalized seizures. Cognitive, cerebellar, motor, and autonomic dysfunctions and brain atrophy were also earlier at onset and more severe than previously reported. Recurrent viral infections are another unique feature. This constellation in tout à fait was not previously reported in the literature.