Paroxysmal Nonkinesigenic Dyskinesia 2

For a general phenotypic description of paroxysmal nonkinesigenic dyskinesia, see PNKD1 (118800).

Clinical Features

Spacey et al. (2006) reported a Canadian family of European descent in which 10 members spanning 4 generations had paroxysmal nonkinesigenic dyskinesia (PNKD) inherited in an autosomal dominant pattern. Affected family members presented with episodic dystonia primarily affecting the hands and feet symmetrically. Age at onset ranged from childhood to age 50 years. Episodes lasted 2 to 5 minutes (up to 10 minutes in 1 patient) and occurred daily or several times per month. Alcohol, caffeine, and excitement were not obvious triggers. Three patients also had migraines, 1 had a grand mal seizure at age 11 years, and 1 had a single infantile seizure.

Mapping

By genomewide linkage analysis of a large family with PNKD, Spacey et al. (2006) identified a candidate locus, termed PNKD2, on chromosome 2q31 (parametric lod score of 2.03 and multipoint nonparametric lod score of 7.0). Haplotype analysis delineated a 10-cM interval between markers D2S2188 and D2S364, and demonstrated a disease penetrance of 89%. Linkage analysis excluded the PNKD1 locus, and molecular analysis did not identify any mutations in the MR1 (609023) or GAD1 (605363) genes.