Epileptiform mice, a new neurological mutant

A new mutant showing epileptiform seizures is described in mice. The condition is determined by an autosomal recessive allele, with penetrance above 90 percent. The name epileptiform and the symbol epf are proposed for this mutation. First appearance of seizure behavior varies from the 20th day to as late as 14 months, with 98 percent becoming convulsive by the 140th day. Life spanis normal (average, 11.6 months). Average litter size of epf/epf mothers is 4.04 ± 1.7 S.D. Matings of epf/epf males × +/epf females yield an average litter size of 6.2 ± 2.7 S.D. Heterozygous animals appear normal and epileptiform mice are indistinguishable from unaffected litter mates except in seizure susceptibility. Seizures may be induced by a range of mild stimuli, including physical, visual, and auditory. Subjects are most susceptible after a period of rest. The seizure pattern involves a tonic phase, a clonic phase, and a post-ictal recovery period. The tonic phase includes strong toxic flexions and extensions of all four limbs, often with distinct emprosthotonus and opisthotonus of the body. The clonic phase is marked by varying degrees of clonic activity, ranging from limb twitching to violent thrashing movements of limbs and tail. Affected mice are refractory to additional seizures for a varying period of time. Fatal outcome (status epilepticus) occurs rarely (5 percent). Comparisons are made of epf seizure pattern with those of other seizure prone animals, and with grand mal epilepsy in man.