KCNJ2 and thyrotoxicosis: Risk allele C of rs312691 downregulated KCNJ2 expression compared with reference allele T. KCNJ2 mutations could lead to Andersen-Tawil syndrome, a disease characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features.30 Moreover, thyrotoxicosis dramatically promoted periodic paralysis in a patient with Andersen-Tawil syndrome with a de novo c.G899C mutation in KCNJ2. 31