A genetically determined basic mechanism in benign partial epilepsies and related non-convulsive conditions

The classification of benign partial epilepsies and related conditions includes (besides rolandic epilepsy) atypical benign partial epilepsy, bioelectrical status epilepticus and a variety of other syndromes. The broad overlap of the clinical and bioelectrical symptomatology might reflect a pathogenetic background common to these epilepsies. In order to understand the great phenotypic variability, the clinical symptomatology in 51 sibships with focal sharp waves of genetic origin was analyzed. A genetic determination was assumed if in addition to the index case at least one sib or offspring revealed typical focal sharp waves. The 51 index-cases and their 57 sibs/offspring showed a broad spectrum of epileptic and non-epileptic conditions ranging from mild selective performance deficits to severe complex psychomental retardation, from simple rolandic epilepsy to severe epilepsies with minor seizures or bioelectrical status. The different conditions are not disease entities but sets of variably weighted symptoms of a complex pathogenetic background, in which a genetic disposition to focal anomalies of brain function is of decisive importance. As can be demonstrated by the data, this genetic 'focal liability' coincides with other widespread genetic traits, expressed in certain EEG patterns, as well as with lesional pathogenetic factors. The biological background of the genetic focal anomaly is unknown up to date. The marked age dependence of the symptoms justifies the assumption of an hereditary impairment of brain maturation.