PubMed · 14002106
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H T WYCIS. 1962. Case demonstrations.. https://doi.org/10.1159/000104367
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BACKGROUND: Paroxysmal dystonic choreoathetosis (PDC) is characterized by attacks of involuntary movements that occur spontaneously while at rest and following caffeine or alcohol consumption. Previously, we and others identified a locus for autosomal dominant PDC on chromosome 2q33-2q35. OBJECTIVE: To identify the PDC gene. DESIGN: Analysis of PDC positional candidate genes by exon sequencing and reverse transcription-polymerase chain reaction. SETTING: Outpatient clinical and molecular genetic laboratory at a university hospital. Patients Affected (n = 12) and unaffected (n = 26) subjects from 2 unrelated families with PDC and 105 unrelated control subjects. RESULTS: We identified missense mutations in the myofibrillogenesis regulator gene (MR-1) in affected subjects in 2 unrelated PDC kindreds. These mutations were absent in control subjects and caused substitutions of valine for alanine at amino acid positions 7 and 9. The substitutions disturb interspecies conserved residues and are predicted to alter the MR-1 gene's amino-terminal alpha helix. The MR-1 exon containing these mutations (exon 1) was expressed only in the brain, a finding that explains the brain-specific symptoms of subjects with these mutations. CONCLUSIONS: Although MR-1 gene function is unknown, the precedence of ion channel disturbance in other episodic neurologic disorders suggests that the pathophysiologic features of PDC also involve abnormal ion localization. The discovery that MR-1 mutations underlie PDC provides opportunities to explore this condition's pathophysiologic characteristics and may provide insight into the causes of other paroxysmal neurologic disorders as well as the neurophysiologic mechanisms of alcohol and caffeine, which frequently precipitate PDC attacks.
The term athetosis has progressively disappeared from the anglo-saxon literature which considers that athetosis is part of the spectrum of dystonia. These two clinical entities can be distinguished, however. Athetosis can be identified, searching for subtle semiological traits, in particular at the level of the hand. The earlier appearance of athetosis may be result from its onset during the early phases of development of the central nervous system. Despite its rarity, the clinical diagnosis of athetosis is important to consider from a prognostic point of view. Indeed, it results from brain lesions, and is therefore not a hereditary disorder as it may be the case for dystonia, and its evolution is relatively stable. The efficacy of treatments used in patients with dystonia, in particular high frequency pallidal stimulation, remains to be assessed in patients with athetosis. The concept of athetosis is still helpful in clinical practice.
A case of late-onset idiopathic paroxysmal kinesigenic choreoathetosis (PKC) is described herein. A 50-year-old right-handed Japanese man with no family history of neurological disease or consanguinity was referred to our neurological unit because of paroxysmal involuntary movement of his right extremities. Physical examination findings were normal. Neurological examination during the interictal period revealed no abnormality. The attacks were triggered by abrupt initiation of voluntary movement and occurred about 30 times a day, lasting 30 to 60 seconds with no disturbance of consciousness. No metabolic abnormalities were found, and brain magnetic resonance imaging showed no abnormality including lacunar infarction. Interictal single photon emission computed tomography (SPECT) showed hypoperfusion of left basal ganglia. Interictal electroencephalography was normal without epileptic discharges. Because the patient did not have any condition that could cause secondary PKC, he was diagnosed as having idiopathic PKC. Treatment with carbamazepine 200 mg once a day resulted in control of the attacks, and 500 mg a day resulted complete resolution. To the best of our knowledge, this case may represent the oldest age reported for idiopathic PKC onset. Although the etiology of PKC remains unknown, late-onset idiopathic PKC is rare. Our SPECT finding leads us to suppose that dysfunction of the basal ganglia is likely involved in the pathogenesis of PKC.