Ataxic mouse mutants and molecular mechanisms of absence epilepsy

Mouse genetic models for common human diseases have been studied for most of the 20th century. Although many polygenic strain differences and spontaneous single gene mutants have been extensively characterized over the years, knowing their innermost secrets ultimately requires the identity of the mutated genes. One group of neurological mutants, detected initially due to cerebellar dysfunction, was identified as models for epilepsy when they were unexpectedly found to have spike-wave seizures associated with behavioral arrest, a central feature of absence or petit-mal epilepsy. A further surprise was that recently identified defective genes encode different subunits of voltage-gated Ca(2+)channels (VGCCs), implying common seizure mechanisms. In this review we first consider these spontaneous mutants with VGCC defects in the context of other mouse models for epilepsy. Then, from the new wave of genetic and functional studies of these mutants we discuss their prospects for yielding insight into the molecular mechanisms of epilepsy.