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Andersen-Tawil syndrome with early fixed myopathy
Stela Lefter1, Orla Hardiman, Donal Costigan
1*Department of Neurology, Cork University Hospital, Cork, Ireland; †Department of Neurology, Beaumont Hospital, Dublin, Ireland; ‡Mater Private Hospital, Dublin, Ireland; §Department of Neurology, Children's University Hospital, Dublin, Ireland; ¶Department of Neurology, Belfast City Hospital, Northern Ireland, United Kingdom; and ‖Department of Pathology, University College Cork, Cork, Ireland.
Journal of Clinical Neuromuscular Disease
|November 22, 2014
Summary
Andersen-Tawil syndrome (ATS) is a rare potassium channelopathy. This case highlights a unique presentation in an Irish patient with early fixed myopathy and a novel KCNJ2 mutation.
Area of Science:
- Genetics and Molecular Biology
- Neurology
- Cardiology
Background:
- Andersen-Tawil syndrome (ATS) is a rare autosomal dominant potassium channelopathy.
- Characterized by periodic paralysis, ventricular arrhythmias, and dysmorphic features.
Observation:
- A 19-year-old Irish male presented with childhood-onset proximal lower limb weakness and neonatal focal seizures.
- He exhibited characteristic skeletal dysmorphic features, evolving from nonfluctuating to fluctuating weakness and a fixed proximal myopathy.
- ECG revealed prominent 'U' waves; exercise testing showed significant compound motor action potential amplitude decline.
Findings:
- Genetic analysis identified a de novo heterozygous R218W mutation in the KCNJ2 gene, confirming ATS.
- This represents the first reported case of ATS in an Irish population.
- The patient displayed an unusual fixed myopathy presentation from early childhood.
Implications:
- This case expands the clinical spectrum of Andersen-Tawil syndrome, particularly the manifestation of early-onset fixed myopathy.
- Highlights the importance of genetic testing for KCNJ2 mutations in patients with unexplained neuromuscular and cardiac symptoms.
- Contributes to understanding the genetic and phenotypic diversity of potassium channelopathies in different populations.
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