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Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia (CAH) resulting from a mutation in the gene CYP17A1, which produces the enzyme 17α-hydroxylase. [1] [2] It causes decreased synthesis of cortisol and sex hormones, with resulting increase in mineralocorticoid production.
Classic 21-hydroxylase deficiency typically causes 17α-hydroxyprogesterone blood levels >242 nmol/L. [medical citation needed] (For comparison, a full-term infant at three days of age should have <3 nmol/L. Many neonatal screening programs have specific reference ranges by weight and gestational age because high levels may be seen in premature ...
[22] [23] [24] Furthermore, mutations in the CYP17A1 gene are associated with rare forms of congenital adrenal hyperplasia, in particular 17α-hydroxylase deficiency/17,20-lyase deficiency and isolated 17,20-lyase deficiency. Overall, CYP17A1 is an important target for inhibition in the treatment of prostate cancer because it produces androgen ...
The condition of 21-hydroxylase deficiency is screened by measuring serum levels of 17α-hydroxyprogesterone (17-OHP) in the morning and between day 3 and 5 of the menstrual cycle (for females) to reduce the possibility of false positive results. [12] 17-OHP is used as a marker of the 21-hydroxylase enzyme activity since the 1980s. [52]
20,22-Desmolase (P450scc) deficiency: blocks production of all steroid hormones from cholesterol [citation needed]; 3β-Hydroxysteroid dehydrogenase 2 deficiency: impairs progestogen and androgen metabolism; prevents the synthesis of estrogens, glucocorticoids, and mineralocorticoids; causes androgen deficiency in males and androgen excess in females [citation needed]
The 21-hydroxylase deficiency may be caused by macrodeletions of about 30 Kb, which includes not only most of the 5′ region of the CYP21A2 gene, but also all of the C4B gene and 3′ regions of the CYP21A1P pseudogene. Duplications of CYP21A1P pseudogene and C4B gene are often associated with nonclassic 21-hydroxylase deficiency. [33]
21-deoxycortisol is a marker of congenital adrenal hyperplasia due to 21-hydroxylase deficiency, [2] [1] [3] even in mild (non-classic) cases. [4] [5] It can be also used for newborn screening. [6] The deficiency of the 21-hydroxylase enzyme leads to excess of 17α-hydroxyprogesterone, [7] [8] a 21-carbon (C 21) steroid.
Isolated 17,20-lyase deficiency is a rare disorder caused by genetic mutations in the gene CYP17A1, while not affecting 17α-hydroxylase. [2] [4] [6] [7] Isolated 17,20 lyase deficiency is a rare disease with only a small number of confirmed reports due to mutations in the CYP17A1 gene.