Bioptically demonstrated Lafora disease without EPM2A mutation: a clinical and neurophysiological study of two sisters

Lafora disease (LD) is an autosomal recessive inherited form of progressive myoclonic epilepsy with dementia and ataxia, usually presenting in the second decade of life and inexorably progressing until death. Neuropathological hallmarks are Lafora bodies, intracytoplasmic inclusions that can be found in neurons and in other tissues. LD gene (EPM2A), mapping on chromosome 6, encodes for a tyrosine phosphatase protein called laforin. However, up to 20% cases of LD are not genetically linked to chromosome 6. We report two sisters affected from bioptically diagnosed LD but without evidence of EPM2A mutation. Although familial cases of LD are already reported in literature, our observation leads to some considerations on clinical-electrophysiological evolution as well as to remark the genetic heterogeneity of this condition. In addition, we report the good effect of the Levetiracetam for the treatment of myoclonus in these patients, also demonstrated by the electrophysiological findings.