There were no differences in the KCNJ2 protein levels according to the GAP stage (stage I vs. II vs. III: 6.692 [1.244–26.59] ng/mL vs. 3.791 [1.676–17.10] ng/mL vs. 19.34 [3.142–42.10] ng/ml; Supplemental ), smoking status (SM vs. ES vs. NS: 7.765 [1.151–25.42] ng/mL vs. 6.375 [1.483–16.28] ng/mL vs. 6.692 [1.489–28.83] ng/mL; Supplemental ), sex (males vs. females: 6.375 [1.398–25.13] ng/mL vs. 6.692 [1.489–27.03] ng/mL; Supplemental ), or presence of arrhythmia (arrhythmia vs. no arrhythmia: 2.582 [0.596–3.232] ng/mL vs. 1.208 [0.239–3.975] ng/mL; Supplemental ). The gene discussed is KCNJ2; the disease is cardiac arrhythmia.