Management and treatment of Andersen-Tawil syndrome (ATS)

Andersen-Tawil syndrome (ATS) is characterized by periodic paralysis, cardiac arrhythmias, and distinct facial and skeletal features. The majority of patients with ATS (ATS1) have point mutations in the KCNJ2 gene, which encodes the inward-rectifying potassium channel known as Kir2.1. The skeletal muscle and cardiac symptoms are accounted for, in most cases, by a dominant negative effect of the mutations on potassium channel current, resulting in prolonged depolarization of the action potential. Mechanisms of disruption of channel function include abnormal trafficking and assembly of second messengers such as phosphatidylinositol 4,5-bisphosphate, abnormal gating of the channel, and incorrect folding of the Kir2.1 protein. Less apparent is the mechanism by which these mutations account for the typical facial and skeletal abnormalities. The concomitant involvement of cardiac and skeletal muscle in ATS poses unique treatment and management challenges. Because of differences in cardiac and skeletal muscle physiology, drugs that may have a beneficial effect on cardiac function may have a detrimental effect on skeletal muscle and vice versa. We review the clinical, laboratory, and genetic features of this disorder with particular emphasis on treatment and management.