Mood disorders such as depression are among the most common mental health problems, and are more frequent in women as in men. It has been long recognized that, in women, the premenstrual, postpartum, and perimenopausal period are linked to an increased risk of mood disorders, and that hormonal fluctuations are likely to play a role. Strikingly, why some women develop these hormone-related mood disorders, and others do not, is currently unknown. This project focuses on studying the genetics of sex hormones (e.g., estrogen) and hormone-related mood disorders in an effort to uncover novel biomarkers and improve prevention and treatment efforts.