The criteria for exclusion of the study were as follows: systematic reviews that did not pool data or carry out meta-analysis; narrative reviews; studies of the efficacy or safety of SGLT-2 inhibitors in patients that did not have heart failure; studies that did not compare SGLT-2 inhibitors with placebo and only evaluated individual factors in heart failure patients such as age, diabetes status, gender, or baseline therapy. The gene discussed is SLC5A2; the disease is diabetes mellitus.