Familial paroxysmal kinesigenic choreoathetosis: an electrophysiologic and genotypic analysis

We report a pedigree of familial paroxysmal kinesigenic choreoathetosis (PKC) in which five of 18 members are affected. The pathophysiologic basis for PKC is still uncertain; reflex epilepsy versus dysfunction of basal ganglia. We examined (a) whether there were ictal discharges during the attacks, and (b) a linkage between PKC and possible DNA markers linked to several familial epileptic or movement disorders.

Video-monitoring EEG was performed in two patients with PKC during attacks elicited by movements of the lower extremities. Blood samples for DNA studies were obtained from 15 members of the pedigree. Fourteen polymorphic markers on chromosomes 1p, 2q, 6p, 10q, and 20q were genotyped, and two-point lod scores were calculated for each marker under a dominant model.

No ictal discharges were found during the attacks in both patients. We could not obtain significant linkage of PKC with any marker examined.

The video-monitoring EEG findings in our cases strongly suggested that the etiology of PKC should be considered distinct from that of reflex epilepsy. However, the patients in this pedigree had experienced generalized convulsions in their infancies; thus we could not deny the possibility of an epileptogenic basis for PKC. There was no strong evidence for a linkage of the gene for PKC with the candidate regions on 1p, 2q, 6p, 10q, or 20q.