Blood pressure is determined by the product of cardiac output, intravascular volume, and peripheral resistance. Because hormones are involved in blood pressure regulation and affect these parameters, hypertension is a prominent feature of certain adrenal enzymatic abnormalities. In this report, two steroid-dependent forms of genetic low-renin hypertension are examined: 11β-hydroxylase deficiency and apparent mineralocorticoid excess. 11β-Hydroxylation is an enzymatic function necessary for the biosynthesis of cortisol by the zona fasciculata (ZF) of the adrenal cortex. Defects in this step lead to the abnormally increased production by the ZF of the steroid 11-deoxycorticosterone (DOC), a moderately potent mineralocorticoid, which causes sodium retention and volume expansion that result in hypertension. Further, the excess production of adrenal androgens leads to virilization, prenatally in the genetic female, and postnatally in both sexes. The disorder of 11β-hydroxylase deficiency is due to an autosomal recessive defect of the enzyme protein-encoding gene CYP11B1. Numerous mutations in CYP11B1 causing 11β-hydroxylase deficiency have been characterized. Apparent mineralocorticoid excess is a potentially fatal genetic disorder causing severe juvenile hypertension, pre- and postnatal growth failure, and low to undetectable levels of potassium, renin, and aldosterone. It is caused by autosomal recessive mutations in the HSD11B2 gene, which result in a deficiency of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2).
- 11β-hydroxylase deficiency
- 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2)
- Apparent mineralocorticoid excess