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Paroxysmal kinesigenic dyskinesia associated with a novel POLG variant: A case report
Yaping Zhou1, Jian Zhang, Xiaoting Wang
1Department of Neurology, The First Hospital of China Medical University, Heping District, Shenyang, China.
Introduction:
Paroxysmal kinesigenic dyskinesia (PKD) is a rare neurological disease characterized by recurrent dyskinesia or choreoathetosis triggered by sudden movements. Pathogenic variants in PRRT2 are the main cause of PKD. However, only about half of clinically diagnosed PKD patients have PRRT2 mutations, indicating that additional undiscovered causative genes could be implicated. PKD associated with POLG variant has not been reported.
Patient Concerns:
A 14-year-old boy presented with a 2-month history of involuntary dystonic movements triggered by sudden activities. He was conscious during the attacks. Neurological examination, laboratory tests, brain magnetic resonance imaging (MRI), electroencephalogram (EEG) were all normal. Genetic analysis showed a novel variant of POLG (c.440G>T, p.Ser147Ile), which was considered to be a likely pathogenic variant in this case.
Diagnoses:
The patient was diagnosed with PKD.
Interventions:
Low dose carbamazepine was used orally for treatment.
Outcomes:
The patient achieved complete resolution of symptoms without any dyskinesia during the 6-month follow up.
Conclusion:
Our study identified the novel POLG variant (c.440G>T, p.Ser147Ile) to be a likely pathogenic variant in PKD.
Insights
Paroxysmal kinesigenic dyskinesia (PKD) is a rare neurological disorder. A novel POLG gene variant was identified as a likely cause in a patient, leading to complete symptom resolution with carbamazepine treatment.
Area of Science:
- Genetics
- Neurology
- Rare Diseases
Background:
- Paroxysmal kinesigenic dyskinesia (PKD) is a rare neurological disorder characterized by involuntary movements triggered by sudden actions.
- While PRRT2 gene variants are the primary cause, approximately half of PKD patients lack these mutations, suggesting other genetic factors.
- PKD associated with POLG variants has not been previously reported.
Observation:
- A 14-year-old male presented with recurrent dystonic movements upon sudden activity.
- Clinical evaluations including neurological exams, MRI, and EEG were normal.
- Genetic analysis revealed a novel POLG variant (c.440G>T, p.Ser147Ile).
Findings:
- The novel POLG variant (c.440G>T, p.Ser147Ile) was identified as a likely pathogenic cause of PKD in this patient.
- The patient received low-dose carbamazepine treatment.
- Complete resolution of dyskinetic symptoms was observed during a 6-month follow-up period.
Implications:
- This study identifies a novel POLG variant associated with paroxysmal kinesigenic dyskinesia.
- It expands the genetic landscape of PKD beyond PRRT2 mutations.
- This finding may contribute to improved genetic diagnosis and targeted therapies for PKD patients.
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