CYP19A1 and Perrault syndrome: This manifests in a range of clinical phenotypes including ovarian insufficiency occurring in isolation (Primary Ovarian Insufficiency, POI; also known as Premature Ovarian Insufficiency), as a feature of an extra-ovarian syndrome (e.g., Perrault Syndrome), or as part of a Difference of Sex Development (DSD) (e.g., aromatase [CYP19A1] deficiency).