Congenital adrenal hyperplasia (CAH) is most often due to a deficiency in 21-hydroxylase. A number of other enzyme deficiencies may also lead to the syndrome.
These enzymes affect the pathways from cholesterol to end-steroids (aldosterone, cortisol, estradiol, DHT and androstenediol).
Shared features:
(1) impaired cortisol synthesis
(2) chronic elevation of serum ACTH
(3) hyperplasia of the adrenal cortex due to effects of ACTH
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Enzyme
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Gene
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3-beta-hydroxysteroid dehydrogenase type 2
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HSD3B2
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17-alpha-hydroxylase
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CYP17A1
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11-beta-hydroxylase
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CYP11B1
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steroidogenic acute regulatory protein
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STAR
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3-beta-hydroxysteroid dehydrogenase type 2
(1) androgen deficiency, with males undervirilized at birth
(2) mineralocorticoid deficiency, with salt wasting
(3) accumulation of pregnenolone, DHEA, 17-hydroxypregnenolone
17-alpha-hydroxylase
(1) androgen deficiency, with males undervirilized at birth
(2) excess mineralocorticoids, with hypertension
(3) accumulation of pregnenolone and progesterone
11-beta-hydroxylase
(1) androgen excess, with virilization
(2) mineralocorticoid excess, with hypertension
(3) accumulation of deoxycorticosterone
steroidogenic acute regulatory protein
(1) androgen deficiency, with males undervirilized at birth
(2) mineralocorticoid deficiency, with salt wasting
