Referenced in: none

Automatically associated channels: Kir2.1

Title: Andersen-Tawil syndrome with early fixed myopathy.

Authors: Stela Lefter, Orla Hardiman, Donal Costigan, Bryan Lynch, John McConville, Collette K Hand, Aisling M Ryan

Journal, date & volume: J Clin Neuromuscul Dis, 2014 Dec , 16, 79-82

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25415519

Abstract
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.