Erectile dysfunction and hypogonadism often coexist in aging men, and androgens may also have a direct association with the corpora cavernosa.11 The latter led some researchers to evaluate erectile function improvement after combination therapy of testosterone and PDE5 inhibitors in patients with hypogonadism.47,48,50 The results of this study point toward an additive efficacy of combination treatment compared to monotherapy. The gene discussed is PDE5A; the disease is erectile dysfunction.