In patients with hyponatremia < 130 mmol/L, significantly elevated levels of renin (< 130 mmol/L: 1283.0 [2204.2] μIU/mL vs. ≥ 130 mmol/L: 34.6 [120.0] μIU/mL, p < 0.001) and copeptin (< 130 mmol/L: 32.3 [19.2] pmol/L vs. ≥ 130 mmol/L: 9.9 [17.3] pmol/L, p = 0.023) were recorded, while there was no significant difference in plasma levels of proBNP (< 130 mmol/L: 156.0 [302.4] pg/mL vs. ≥ 130 mmol/L: 129.0 [289.9] pg/mL, p = 0.797) (Fig. S2). The gene discussed is REN; the disease is Hyponatremia.