FKBP5 is currently being studied as a potential biomarker for cortisol activity in 2 ongoing phase 3 studies of the investigational selective GR modulator relacorilant (Corcept Therapeutics, Menlo Park, CA) in patients with endogenous CS (NCT03697109, NCT04308590). Here, NR3C1 is linked to Cowden syndrome 1.