Paroxysmal Nonkinesigenic Dyskinesia 1 (PKND) is a rare, episodic movement disorder, characterized by involuntary dystonic, choric, ballismic, or athetosic attacks of unilateral or bilateral involvement. These spontaneous hyperkinetic attacks last from minutes to hours, rarely occur more than once per day, and are usually precipitated by caffeine or alcohol intake, or stress and fatigue. The attacks may be accompanied by a preceding aura, and occur while the individual is awake. The usual age of onset of these attacks is in childhood or the early teens.
Diagnosis of PNKD is based on the clinical features. This condition is characterized by normal ictal and interictal EEG, and MRI. Therefore, neurological assessment and MRI ought to be performed to exclude any other causes of the clinical features. The condition tends to show poor response to medications.
Familial PNKD is inherited in an autosomal recessive manner. The only gene shown to be responsible for the development of this disease is the MR1 (Myofibrillogenesis Regulator gene 1) gene. The product of this gene has been shown to interact with contractile proteins of the muscle, and thereby play a role in muscle contraction.