HSD11B2

HSD11B2, also known as 11-beta-hydroxysteroid dehydrogenase type 2, is an enzyme encoded by the HSD11B2 gene. This gene is located on chromosome 16q22.1 in humans. The HSD11B2 enzyme plays a critical role in regulating the effects of glucocorticoids and mineralocorticoids within the body. Specifically, it catalyzes the conversion of cortisol to cortisone and corticosterone to 11-dehydrocorticosterone in mineralocorticoid-sensitive tissues, such as the kidneys. This inactivation of active glucocorticoids prevents them from binding to and activating the mineralocorticoid receptor, thereby preserving the selectivity of mineralocorticoid action.

Mutations in the HSD11B2 gene can lead to a rare genetic disorder called apparent mineralocorticoid excess (AME). In individuals with AME, the deficiency or inactivity of HSD11B2 leads to the inappropriate accumulation of cortisol in mineralocorticoid-sensitive tissues. This excess cortisol then binds to and activates the mineralocorticoid receptor, mimicking the effects of aldosterone. Consequently, patients with AME exhibit symptoms such as hypertension, hypokalemia, and metabolic alkalosis, which can be severe and life-threatening if not managed. The HSD11B2 enzyme is thus crucial for maintaining electrolyte balance and blood pressure homeostasis.