Paroxysmal kinesigenic choreoathetosis (PKC), characterised by brief attacks of abnormal involuntary movements induced by sudden voluntary movements, is either idiopathic (familial or sporadic) or symptomatic. A total of about 20 families with PKC have been reported, with autosomal dominant inheritance in most of them. No genetic study has been reported in familial PKC up to now.

We report two unrelated families with autosomal dominant PKC, in which we performed linkage analyses with loci involved in other paroxysmal movement disorders: (1) the locus for paroxysmal dystonic choreoathetosis (PDC), also known as paroxysmal nonkinesigenic dyskinesia, on chromosome 2q33–35,1 (2) the locus for AD paroxysmal choreoathetosis/spasticity (CSE), classified as “complicated” PDC, on chromosome 1p,2 and (3) the locus for episodic ataxia/myokymia (EA-1) on chromosome 12p13.3

Family A was Portuguese and family B was French. They contained a total of 10 affected and nine unaffected family members, who were all interviewed and examined by the same physician. There was no family history of epilepsy. In one family, three of the five affected members also had migraine with visual aura. Except for one patient, who had had a parkinsonian resting tremor since the age of 52, neurological examination was normal. The phenotypes of the 10 patients were very …