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An expected second 17,20-lyase reaction (17α-hydroxyprogesterone → androstenedione) is mediated so inefficiently in humans as to be of no known significance. The hydroxylase reactions are part of the synthetic pathway to cortisol as well as sex hormones, but the lyase reaction is only necessary for sex hormone synthesis.
Mutations in this gene are associated with rare forms of congenital adrenal hyperplasia, specifically 17α-hydroxylase deficiency/17,20-lyase deficiency and isolated 17,20-lyase deficiency. [21] In humans, the CYP17A1 gene is largely associated with endocrine effects and steroid hormone metabolism. [22] [23] [24] Furthermore, mutations in the ...
CAH due to 21-hydroxylase deficiency is the most common cause of ambiguous genitalia in genotypically normal female infants (46XX). Less severely affected females may present with early pubarche. Young women may present with symptoms of polycystic ovarian syndrome (oligomenorrhea, polycystic ovaries, hirsutism). [medical citation needed]
The symptoms of isolated 17,20-lyase deficiency, in males, include pseudohermaphroditism (i.e., feminized, ambiguous, or mildly underdeveloped (e.g., micropenis, perineal hypospadias, and/or cryptorchidism (undescended testes)) external genitalia), female gender identity, and, in non-complete cases of deficiency where partial virilization occurs, gynecomastia up to Tanner stage V (due to low ...
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]
Other causes, albeit less frequent, are mutations in genes affecting other enzymes involved in steroid metabolism, like 11β-hydroxylase or 3β-hydroxysteroid dehydrogenase. [3] It has a prevalence between 0.1% and 2% depending on population, [2] and is one of the most common autosomal recessive genetic diseases in humans.
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]
Dopamine beta (β)-hydroxylase deficiency is a human medical condition involving inadequate dopamine beta-hydroxylase. It is characterized by increased amounts of serum dopamine and the absence of norepinephrine (NE) and epinephrine. Dopamine is released, as a false neurotransmitter, in place of norepinephrine (aka noradrenaline and ...