Familial paroxysmal nonkinesigenic dyskinesia: Clinical and genetic analysis of a Taiwanese family

Paroxysmal nonkinesigenic dyskinesia (PNKD) is a rare disorder in autosomal dominant inheritance. The clinical features and genetic findings of PNKD, rarely described in the Asians, were mostly delineated from European families. The present study characterized the clinical and genetic findings of a Taiwanese PNKD family. The clinical features of our five patients in successive three generations included onset age less than 10 years, attack duration between 3 min and 4 h, and a variety of aura symptoms. The attacks were provoked not by sudden action but by emotional stress, caffeine, fatigue, heavy exercise and sleep deprivation. Sleep could abolish or diminish the attack and the attacks responded well to clonazepam. Sequencing the whole coding region of PNKD/MR-1 gene identified a heterozygous c.20C>T (p.Ala7Val) mutation which was clearly segregated in the five affected patients. Comparing our patients with previously reported 18 families with PNKD/MR-1 mutations, the majority of the patients exhibited quite similar manifestations in attack patterns and precipitating factors. The recurrent conservative mutations in different ethnicities indicate importance in the pathogenesis of PNKD.