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hydroxylase
(redirected from 21-Hydroxylase)

   Also found in: Encyclopedia, Wikipedia 0.02 sec.
hydroxylase /hy·drox·y·lase/ (hi-drok´sĭ-lās) any of a group of enzymes that catalyze the formation of a hydroxyl group on a substrate by incorporation of one atom (monooxygenases) or two atoms (dioxygenases) of oxygen from O2.
11β-hydroxylase  an enzyme that catalyzes the hydroxylation of steroids at the 11 position, a step in the synthesis of steroid hormones; deficiency causes a form of congenital adrenal hyperplasia.
17α-hydroxylase  an enzyme that catalyzes the oxidation of steroids at the 17 position, steps in the synthesis of steroid hormones; deficiency causes a form of congenital adrenal hyperplasia and if it occurs during gestation can cause male pseudohermaphroditism.
18-hydroxylase  an enzyme that catalyzes several steps in the biosynthesis of aldosterone from corticosteroids; deficiency causes salt wasting.
21-hydroxylase  an enzyme that catalyzes the hydroxylation of steroids at the 21 position, a step in the synthesis of steroid hormones; deficiency impairs the ability to produce all glucocorticoids and causes a form of congenital adrenal hyperplasia.

hy·drox·yl·ase (h-drks-ls, -lz)
n.
Any of various enzymes that catalyze the formation of hydroxyl groups by oxidation of the substrate.

hydroxylase
any enzyme that brings about the coupled oxidation of two donors, with incorporation of oxygen into one of them.

21-hydroxylase
a partial deficiency of the enzyme, in Pomeranian dogs, is thought to cause a dermatosis; histopathological lesions are of cutaneous atrophy; clinical signs include bilateral alopecia of the trunk, caudal thighs, ventral neck.


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The most common type of CAH is 21-hydroxylase deficiency, within which three severity subtypes are distinguished: Saltwasters (SW), the most severe subtype, in which the enzyme deficiency causes deficiencies of both glucocorticoid (glucose-regulating) and mineralocorticoid (sodium-regulating) hormones; simple virilizers (SV), with moderate deficiencies of glucocorticoids; and the mildest subtype, non-classical (NC), late-onset CAH.
I focused on the most prevalent intersex syndrome, classical (prenatal-onset) congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, and summarized recent psychological research in children and adults with this syndrome, complemented by studies on intersex syndromes in 46, XY individuals.
Amniotic fluid concentrations of delta-5 and delta-4 steroids in fetuses with congenital adrenal hyperplasia due to 21-hydroxylase deficiency and in anencephalic fetuses.
 
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