P162 – 2473: Andersen-Tawil syndrome with myopathy: Case report

Abstract

Introduction Andersen-Tawil syndrome (ATS) is a rare autosomal dominant potassium channelopathy characterized by periodic paralysis, ventricular arrhythmias, and dysmorphic features. We present a 14-year-old boy with characteristic features of ATS, and childhood onset myopathy. Case report Fourteen years old boy admitted to our clinic with progressive muscle weakness and also described periods of severe weakness attacks for the last two years. Birth and family history were normal except 37 weeks of prematurity. At the age of four he started to fall down while walking and he descibed tiredness. At the age of 6 cardiac arrhythmia was detected. Investigations for muscle weakness showed that serum creatine kinase level was 625 U/L. Electromyography showed myopathic changes. The muscle biopsy didn't demonstrate any specific finding. On his examination there was orbital hypertelorism, micrognathia, low set ears, clinodactyly, short stature, proximal muscle weakness of both upper and lower extremities. Deep tendon reflexes were hypoactive, Gowers sign was positive. On his electrocardiogram ventricular extrasystoles and U waves were seen. With the findings of severe worsening of limb weakness and dysmorphic features with cardiac arrhythmia ATS was suspected. Genetic testing confirmed a heterozygous mutation (R218W) in KCNJ2. After acetazolamide treatment attacks of severe muscle weakness and Gowers sign disappeared. Conclusion Although ATS is charactized with episodes of muscle weakness, fixed myophaty had been reported only in two patients previously. All these two patients and our patient had heterozygous mutation (R218W) in KCNJ2. Because of the life threatening cardiac arrhythmias ATS must also be kept in mind in patients with fixed myophaty.