Peer-Reviewed Journal Details
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Lefter S, Hardiman O, Costigan D, Lynch B, McConville J, Hand CK, Ryan AM
Journal of Clinical Neuromuscular Disease
Expanding the phenotype of Andersen-Tawil Syndrome: first Irish case
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Andersen Tawil Syndrome Periodic Paralysis Channelopathy KCNJ2 gene
Andersen-Tawil syndrome (ATS) is a rare autosomal dominant potassium channelopathy characterized by a triad of periodic paralysis, ventricular arrhythmias, and distinctive dysmorphic abnormalities. We present a 19-year-old man with characteristic skeletal dysmorphic features of ATS, early nonfluctuating proximal lower limb weakness from childhood, and neonatal focal seizures. He later developed fluctuating weakness in addition to a fixed proximal myopathy. A 12-lead electrocardiogram showed prominent "U" waves, and McManis protocol prolonged exercise test showed an unusually early decline in the compound motor action potential amplitude by 51%. Genetic testing revealed a de novo heterozygous mutation (R218W) in KCNJ2 associated with ATS. This is the first reported case of ATS in an Irish population with an unusual fixed myopathy from early childhood.
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