Myoclonin1/EFHC1 mutations cause 9% of juvenile myoclonic epilepsy (JME) by impairing apoptosis in neurons/synapses where R type voltage dependent calcium channel function is altered, imbuing susceptibility to myoclonic and grand mal seizures. By disrupting mitotic spindle assembly and radial migration of neuroblasts, mutations could produce abnormal intracortical architecture upon which epileptogenesis is established. For an expanded treatment of this topic see Jasper’s Basic Mechanisms of the Epilepsies, Fourth Edition (Noebels JL, Avoli M, Rogawski MA, Olsen RW, Delgado-Escueta AV, eds) published by Oxford University Press (available on the National Library of Medicine Bookshelf [NCBI] at http://www.ncbi.nlm.nih.gov/books).