In the 2021 European Society of Cardiology (ESC) heart failure (HF) guidelines, sodium–glucose cotransporter 2 (SGLT2) inhibitors were recommended for the prevention of HF in patients with type 2 diabetes mellitus (T2DM) and for the treatment of HF with reduced ejection fraction (HFrEF). The gene discussed is SLC5A2; the disease is hydrops fetalis.