Key result
Genetic testing identifies a KCNJ2 variant, diagnosing Andersen-Tawil syndrome with ventricular arrhythmias.
Why the study?
The diagnosis of Andersen-Tawil syndrome can be delayed when initial symptoms such as myalgia are nonspecific, yet early diagnosis is critical to prevent life-threatening cardiac complications.
Case Report (n=1)
Recognizing atypical presentations of Andersen-Tawil syndrome, such as myalgia and elevated creatine kinase levels, via careful attention to dysmorphic features, family history, and electrophysiological testing is critical for initiating appropriate cardiac surveillance for ventricular arrhythmias.
Answers are grounded in this paper and cite their sources.
Early recognition of myalgia with elevated CK may prompt ATS evaluation to avert arrhythmias; extends phenotypic spectrum but remains hypothesis-generating.
Background Andersen-Tawil syndrome (ATS) is a rare, autosomal dominant disorder characterized by a triad of periodic paralysis, ventricular arrhythmias, and dysmorphic features. The diagnosis of ATS can be delayed if the initial symptoms, such as myalgia, are nonspecific. Early diagnosis is critical to prevent life-threatening cardiac complications. Case presentation A 14-year-old boy was referred for the evaluation of episodic myalgia, fatigue, and an incidentally elevated creatine kinase (CK) level. Based on the presence of characteristic facial features, a dental anomaly, and clinodactyly, along with a history of hypokalemic paralysis in the father, ATS was suspected. A long exercise test demonstrated a significant decrease in compound muscle action potential (CMAP) amplitude, suggesting periodic paralysis. Genetic testing identified a previously reported heterozygous variant, c.921G>A (p.Met307Ile), in KCNJ2 , confirming the diagnosis of ATS. Holter monitoring revealed ventricular arrhythmias. The same genetic variant and cardiac arrhythmias were identified in the patient's father and sister. Conclusion This case describes an atypical presentation of ATS with myalgia and elevated serum CK levels, which requires differentiation from muscular dystrophy. Careful attention to dysmorphic features and family history, along with electrophysiological testing, is useful for early diagnosis. The recognition of atypical presentations is essential for initiating appropriate cardiac surveillance and preventing potentially fatal outcomes.
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Ando et al. (2026) conducted a case report in Andersen-Tawil syndrome (n=1). Genetic testing and electrophysiological evaluation (long exercise test and Holter monitoring) was evaluated on Diagnosis of Andersen-Tawil syndrome and detection of ventricular arrhythmias. Genetic testing in a 14-year-old boy with myalgia and elevated CK identified a heterozygous KCNJ2 variant (c.921G>A), confirming Andersen-Tawil syndrome with ventricular arrhythmias.
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