Four types of monogenic
hypertension belong to the group of
mineralocorticoid hypertension, which are characterized by high renal water and
sodium retention and resulting suppression of plasma
renin activity (PRA), high urinary
potassium secretion and consecutive low plasma
potassium:1. increased production of the
hormone aldosterone:
glucocorticoid-remediable aldosteronism (GRH), 2. prereceptor disorder with loss of selectivity of the
mineralocorticoid receptor: apparent
mineralocorticoid excess (
AME), 3. receptor disorder with constitutive activation of the
mineralocorticoid receptor: "Geller syndrome", 4. postreceptor disorder with enhanced function of the
epithelial sodium channel: Liddle's syndrome. While in GRH high synthesis of
aldosterone results in high plasma
aldosterone and low PRA, in the primary renal malfunctions of the
AME, constitutive activation of the
mineralocorticoid receptor and the Liddle's syndrome both plasma
aldosterone and PRA are low. These forms of
hypertension are rather rare in their complete expression, but they point to candidate genes whose mutations may predispose to
hypertension. A point mutation of the
ENaC beta-subunit (T594M) occurs rather frequent in people of African origin, with 5%. Therefore it is suggested to analyze the genotype of black hypertensive patients as a prerequisite for a rational
amiloride therapy. Contrarily, the rather frequent (A[2139]G) polymorphism of the promoter of the alpha-subunit is supposed to mark a lower risk of
hypertension. Mutations in the
serine-threonine kinases WNK1 or WNK4 cause
pseudohypoaldosteronism type II. WNK1 and WNK4 are expressed in the distal part of the nephron. Stimulation of
sodium reabsorption by
aldosterone is normal but without influence on
hyperkalemia. An extrarenal disorder is suggested to be the cause of autosomal-dominant
hypertension with brachydactyly: the patients react with a severely impaired baroreflex und show neurovascular contact. The mutation causing this syndrome is not known.