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3. What are the enzymes common for adrenal and gonadal steroidogenesis?

The enzymes which are common for adrenal and gonadal steroidogenesis

include side-chain cleavage (20,22 desmolase or CYP11A1), 17α-hydroxylase

(CYP17A1), and 3β-hydroxysteroid dehydrogenase type 2 (3β-HSD2). Hence,

defi ciency of these enzymes not only results in impaired cortisol synthesis but

also defective gonadal steroidogenesis.

4. How to classify CAH due to 21α - hydroxylase defi ciency?

Depending on the residual enzymatic activity, CAH due to 21α-hydroxylase

defi ciency is classifi ed as classical or non-classical variants. The classical vari-

ant is further subclassifi ed as salt-wasting (75 %) and simple virilizing (25 %)

forms. Patients with salt-wasting variant have residual 21α-hydroxylase enzy-

matic activity <1 %; those with simple virilizing have 1–5 % residual enzymatic

activity and non-classical variant have 20–50 % (Fig. 10.3 ).

Cholesteroldesmolase

(CYP11A1)

3 β-Hydroxysteroid

dehydrogenase

21-Hydroxylase

(CYP21A2)

17 β-Hydroxysteroid

dehydrogenase

11 β(CYP11B2)-Hydroxylase 11 β(CYP11B1)-Hydroxylase 5 α-Reductase

18-Hydroxylase(CYP11B2)

18-Oxidase(CYP11B2)

Cholesterol 17 α-Hydroxylase (CYP17A1) 17,20-Lyase

Pregnenolone

Progesterone

Deoxycorticosterone

Corticosterone

18-OH Corticosterone

Aldosterone

17-OH Pregnenolone

11-Deoxycortisol

17-OH Progesterone

Testosterone

Androstenedione

Dehydroepiandrosterone

Cortisol Dihydrotesterone

CH 3

CH 3

CH 3

CH 3

CH OH 2

1117

17

3

HO OH O 3

(^21) OH
HC=0
Fig. 10.2 Adrenal steroidogenesis
Congenital adrenal hyperplasia
Classical forms Non-classical form
Salt-wasting Simple virilizing
Fig. 10.3 Classifi cation of CAH due to 21α-hydroxylase defi ciency
10 Congenital Adrenal Hyperplasia