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Congenital adrenal hyperplasia encompasses several autosomal recessive disorders with complete or partial deficiency of an enzyme involved in the cortisol or aldosterone synthesis.

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Adrenogenital syndrome
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Ambiguous genitalia in an infant with adrenogenital syndrome.

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Adrenogenital syndrome
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Clitoris hypertrophy in a female with adrenogenital syndrome.

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Adrenal Virilism; Congenital Adrenal Hyperplasia.

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Worldwide, the frequency of the classic form is estimated to be 1:5000 to 1:15,000. However, in Yupik Eskimos of Alaska, the disease occurs in up to 1:300 neonates.

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Most often autosomal recessive inheritance. Spontaneous mutations are possible.

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The common finding in all of these cases is an elevated ACTH level resulting from significantly decreased negative feedback of cortisol on ACTH secretion in the pituitary gland. Congenital adrenal hyperplasia (CAH), which to the histopathologic finding of adrenal cortical hyperplasia, is the result of these elevated ACTH levels. Any of the steps involved in adrenal steroidogenesis can be affected. The classic form, which is responsible for more than 90% of all cases of CAH, is characterized by absent or decreased activity of the enzyme 21-hydroxylase. Whereas the classic form denotes the early diagnosed form of 21-hydroxylase deficiency, the nonclassic form denotes the same enzyme defect with late diagnosis (because of absent salt wasting and developmental abnormalities) and signs of hyperandrogenism. From 5 to 8% of CAH cases are caused by dysfunction of the enzyme 11-β-hydroxylase. In the remainder of patients with CAH, the affected enzyme is either 17α-hydroxylase or 3β-hydroxysteroid dehydrogenase.

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Depending on the affected enzyme, the symptoms can vary widely. Deficiency of 21-hydroxylase, which converts 17α-hydroxyprogesterone to 11-deoxycortisol, results in accumulation of cortisol precursors that are metabolized to adrenal androgens (dehydroepiandrostenedione [DHEA] and androstenedione) instead. Absence of negative feedback on pituitary ACTH secretion, which is caused by a lack of cortisol, potentiates the symptoms. Clinically, the children may present in two forms: “simple virilization” or “salt wasting.” At birth, female infants appear virilized with clitoral enlargement, labial fusion, and/or urogenital sinus. Left untreated, these signs can become even more prominent over time. Sexual development in male infants usually is normal, but excessive androgen production can result in sexual precocity. In up to 70% of all infants, “simple virilization” is accompanied by salt wasting because of a mineralocorticoid deficiency with hyponatremia, hyperkalemia, and hypotension (hypovolemia). Plasma renin activity is elevated, and signs of hypoaldosteronism may occur in the first weeks of life.

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Deficiency in 11-β-hydroxylase, which is needed to convert 11-deoxycortisol and deoxycorticosterone (DOC) to cortisol and corticosterone, also results in decreased cortisol levels ...

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