In the 2021 European Society of Cardiology (ESC) Heart Failure Guidelines, SGLT2 inhibitors were added to the standard treatment for patients with heart failure with HFrEF in addition to beta-blockers, mineralocorticoid receptor antagonists (MRAs), and RAAS blockers/angiotensin receptor-neprilysin inhibitors (ARNI) (Class I recommendation, Level of Evidence A), regardless of diabetic status [185]. The gene discussed is SLC5A2; the disease is heart failure.