KCNJ2 and Andersen-Tawil syndrome: Since ATS is inherited in an autosomal dominant fashion, we overexpressed each HA-tagged Kir2.1 variant (HA-Kir2.1) in a HEK 293 cell line stably expressing MYC-tagged WT Kir2.1 (Myc-Kir2.1) Figure 2A (19).