11β-hydroxylase deficiency pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mehrian Jafarizade, M.D [2]
Overview
11β-Hydroxylase deficient congenital adrenal hyperplasia (11β-OH CAH) is a type of congenital adrenal hyperplasia (CAH) resulting from a defect in CYP11B1 on chromosome 8. This gene encodes an enzyme called 11β-hydroxylase in the path of steroid biosynthesis. 11β-hydroxylase enzyme is located in the zona fasciculate, and converts 11-deoxycortisol to cortisol and 11-deoxycorticosterone corticosterone. Cortisol production reduction has a negative feedback on the pituitary and increases corticotropin (ACTH) secretion. This leads to of 11-deoxysteroid precursors and then adrenocortical hyperplasia. With intact amount of other pathways, as a result of high ACTH concentrations, some amount of the 11-deoxycortisol precursors are metabolized to adrenal androgens and can cause virilization in a genetically female fetus or a child of either sex. Severity of disease depends on the amount of functional 11-beta-hydroxylase enzyme that an individual produces. Aldosterone production is decreased in this disease but there is an elevation of adrenocorticotropic hormone results in overproduction of 11-deoxycorticosterone (DOC) by mid-childhood. 11-Deoxycorticosterone is a weak mineralocorticoid, but because of high amounts in this disease can cause mineralocorticoid excess effects such as salt retention, volume expansion, and hypertension. Nonclassic forms mostly doesn't have verifiable mutations and mild 11β-hydroxylase deficient is currently considered a very rare cause of hirsutism and infertility.
Pathogenesis
- 11β-Hydroxylase deficient congenital adrenal hyperplasia (11β-OH CAH) is a type of congenital adrenal hyperplasia (CAH) resulting from a defect in CYP11B1 on chromosome 8.
- CYP11B1 gene encodes an enzyme called 11β-hydroxylase in the path of steroid biosynthesis. This enzyme is located in the zona fasciculate, and converts 11-deoxycortisol to cortisol and 11-deoxycorticosterone corticosterone.
- Cortisol production reduction has a negative feedback on the pituitary and increases corticotropin (ACTH) secretion. This leads to of 11-deoxysteroid precursors and then adrenocortical hyperplasia.
- With intact amount of other pathways, as a result of high ACTH concentrations, some amount of the 11-deoxycortisol precursors are metabolized to adrenal androgens and can cause virilization in a genetically female fetus or a child of either sex.
- Severity of disease depends on the amount of functional 11-beta-hydroxylase enzyme that an individual produces.
- Aldosterone production is decreased in this disease but there is an elevation of adrenocorticotropic hormone results in overproduction of 11-deoxycorticosterone (DOC) by mid-childhood. 11-Deoxycorticosterone is a weak mineralocorticoid, but because of high amounts in this disease can cause mineralocorticoid excess effects such as salt retention, volume expansion, and hypertension.
- Nonclassic forms mostly doesn't have verifiable mutations and mild 11β-hydroxylase deficient is currently considered a very rare cause of hirsutism and infertility.
Genetics
- 11β-hydroxylase deficiency is an inherited disease with an autosomal recessive pattern, which means both copies of the gene in each cell have gene mutations.
- Commonly, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
- Most CYP11B1 mutations correspond to minimal or absent enzyme activity, resulting in the classic congenital adrenal hyperplasia phenotype.
- A non-classic form of enzyme deficiency caused by CYP11B1 mutations exists but is very rare.[1][2][3]
Associated Conditions
- Hirsurism
- Hypertension
- Testicular tumor
Gross Pathology
On gross pathology the following changes are noted:
- Thickening of adrenal gland
- Cerebriform appearance
Microscopic Pathology
On microscopic pathology the following changes are noted:
- Diffuse cortical hyperplasia
- Zona reticularis is markedly hyperplastic
- Lipid depleted cortical cells
References
- ↑ El-Maouche D, Arlt W, Merke DP (2017). "Congenital adrenal hyperplasia". Lancet. doi:10.1016/S0140-6736(17)31431-9. PMID 28576284.
- ↑ Zachmann M, Tassinari D, Prader A (1983). "Clinical and biochemical variability of congenital adrenal hyperplasia due to 11 beta-hydroxylase deficiency. A study of 25 patients". J. Clin. Endocrinol. Metab. 56 (2): 222–9. doi:10.1210/jcem-56-2-222. PMID 6296182.
- ↑ Hannah-Shmouni F, Chen W, Merke DP (2017). "Genetics of Congenital Adrenal Hyperplasia". Endocrinol. Metab. Clin. North Am. 46 (2): 435–458. doi:10.1016/j.ecl.2017.01.008. PMID 28476231.