Paroxysmal kinesigenic dyskinesia and generalized seizures: Clinical and genetic analysis in a Spanish pedigree

Familial Paroxysmal kinesigenic dyskinesia (PKD) is a rare disorder featuring brief, dystonic or choreoathetotic attacks, typically triggered by sudden movements. Symptoms usually start in mid-childhood, although in several pedigrees infantile convulsions have been reported as the presenting sign. Previous linkage studies have identified two PKD loci on 16 p12.1-q21. We report here the clinical features of a Spanish kindred with autosomal dominant PKD, in which haplotype data are compatible with linkage to the pericentromeric region of chromosome 16 and exclude linkage to the locus for Paroxysmal Non Kinesigenic Dyskinesia (PNKD) on chromosome 2q35. In this family, the conservative candidate region for the disease lies between markers D16S3145 and GATA140E03 on 16p12.1-q21 and partially overlaps with both the Paroxysmal Kinesigenic Dyskinesia - Infantile Convulsions (PKD-IC) critical interval and the Episodic Kinesigenic Dyskinesia 2 (EKD2) locus. Unusual findings in our pedigree were early infantile onset of the dyskinesias in one patient and generalized seizures as adults in two, adding to previous observations of phenotypic overlap between epileptic and non-epileptic paroxysmal disorders. Further clinical and genetic studies are needed to elucidate whether PKD and PKD-IC are allelic disorders with age-dependent phenotypic expression.