Glucocorticoid-Remediable Aldosteronism (GRA)

Glucocorticoid-remediable aldosteronism (GRA), also known as familial hyperaldosteronism type I or glucocorticoid-suppressible hyperaldosteronism, is an autosomal dominant form of low-renin hypertension,.
It is a rare condition that accounts for approximately 2% of all cases of hypertension.

The disorder arises from an unequal meiotic crossing-over event between the closely linked CYP11B1 (11-beta-hydroxylase) and CYP11B2 (aldosterone synthase) genes located on chromosome 8q24.
This recombination creates a chimeric or hybrid gene that fuses the ACTH-responsive promoter sequence of CYP11B1 with the coding sequence of CYP11B2,.
Consequently, an enzyme with aldosterone synthase activity is inappropriately expressed in the zona fasciculata of the adrenal cortex and becomes regulated by adrenocorticotropic hormone (ACTH) rather than the normal renin-angiotensin system,.

Patients typically present in the first two decades of life with early-onset, moderate-to-severe hypertension that may be accompanied by headaches, dizziness, and visual disturbances,.
A strong family history of premature cerebrovascular accidents (strokes) or early-onset hypertension is a classic hallmark.
Biochemically, patients exhibit elevated plasma and urine aldosterone levels alongside persistently suppressed plasma renin activity.
Hypokalemia may occur but is usually mild and is not a consistently present finding,.
A unique and defining biochemical marker of GRA is the marked overproduction of the hybrid steroids 18-hydroxycortisol and 18-oxocortisol, which require both 17-hydroxylase and aldosterone synthase activities to be synthesized,,.

The diagnosis is strongly suggested by a dexamethasone suppression test, which uniquely and rapidly suppresses the hypersecretion of aldosterone and resolves clinical features in GRA,.
Definitive diagnosis is established by molecular genetic testing to detect the presence of the hybrid CYP11B1/CYP11B2 gene.
The primary treatment consists of the daily administration of exogenous glucocorticoids (such as dexamethasone) to chronically suppress pituitary ACTH secretion, thereby halting the aberrant aldosterone synthesis.
In cases where hypertension is long-standing and does not resolve completely with glucocorticoids, additional targeted therapy with potassium-sparing diuretics (e.g., spironolactone, eplerenone, or amiloride) or calcium channel blockers may be required.