Medicine:Pseudohypoaldosteronism
| Pseudohypoaldosteronism | |
|---|---|
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| In pseudohypoaldosteronism, aldosterone is elevated (hyperaldosteronism), but because the body fails to respond to it, it appears similar to hypoaldosteronism. |
Pseudohypoaldosteronism (PHA) is a condition that mimics hypoaldosteronism.[1] However, the condition is due to a failure of response to aldosterone, and levels of aldosterone are actually elevated, due to a lack of feedback inhibition.[citation needed]
Types
| Type | OMIM | Gene | Inheritance | Description |
|---|---|---|---|---|
| PHA1A | Online Mendelian Inheritance in Man (OMIM) 177735 | MLR NRC | Autosomal dominant | with sodium wasting |
| PHA1B | Online Mendelian Inheritance in Man (OMIM) 264350 | SCNN1A, SCNN1B, SCNN1G of the epithelial sodium channel | Autosomal recessive | with sodium wasting |
| PHA2 | Online Mendelian Inheritance in Man (OMIM) 145260 | WNK4, WNK1 | without sodium wasting. TRPV6 may be involved.[2] |
Presentation
PHA2 is clinically characterised by hypertension, hyperkalaemia, metabolic acidosis and normal renal function.[3]
Mechanism
PHA2 is also known as Gordon's syndrome or familial hyperkalemic hypertension. The underlying genetic defect leads to increased sodium chloride reabsorption in the distal tubule in the kidney, leading to volume expansion, hypertension and lowered renin levels. The hyperkalemia found in PHA2 is proposed to be a function of diminished sodium delivery to the cortical collecting tubule (potassium excretion is mediated by the renal outer medullary potassium channel (ROMK) in which sodium reabsorption plays a role). Alternatively, WNK4 mutations that result in a gain of function of the Na-Cl co-transporter may inhibit ROMK activity resulting in hyperkalemia.[4] Unlike in PHA1 in which aldosterone resistance is present, in PHA2 the volume expansion leads to relatively low aldosterone levels.[3]
Treatment
Treatment of severe forms of PHA1 requires relatively large amounts of sodium chloride.[5] These conditions also involve hyperkalemia.[6]
In contrast, PHA2 (Gordon's syndrome) requires salt restriction and use of thiazide diuretics to block sodium chloride reabsorption and normalise blood pressure and serum potassium.[citation needed]
History
This syndrome was first described by Cheek and Perry in 1958.[7] Later pediatric endocrinologist Aaron Hanukoglu reported that there are two independent forms of PHA with different inheritance patterns: A renal form with autosomal dominant inheritance exhibiting salt loss mainly from the kidneys, and a multi-system form with autosomal recessive form exhibiting salt loss from kidney, lung, and sweat and salivary glands.[8][9]
The hereditary lack of responsiveness to aldosterone could be due to at least two possibilities: 1. A mutation in the mineralocorticoid receptor that binds aldosterone, or 2. A mutation in a gene that is regulated by aldosterone. Linkage analysis on patients with the severe form of PHA excluded the possibility of linkage of the disease with the mineralocorticoid receptor gene region.[10] Later, the severe form of PHA was discovered to be due to mutations in the genes SCNN1A, SCNN1B, and SCNN1G that code for the epithelial sodium channel subunits, α, β, and γ, respectively.[11]
A stop mutation in the SCNN1A gene has been shown to be associated with female infertility.[12]
See also
- Hyperchloremic acidosis
- Pseudohyperaldosteronism
References
- ↑ "Pseudohypoaldosteronism: Overview - eMedicine Pediatrics: General Medicine". http://emedicine.medscape.com/article/924100-overview.
- ↑ "Mechanisms for hypercalciuria in pseudohypoaldosteronism type II-causing WNK4 knock-in mice". Endocrinology 151 (4): 1829–36. Apr 2010. doi:10.1210/en.2009-0951. PMID 20181799.
- ↑ 3.0 3.1 O'Shaughnessy, Kevin M. (November 2015). "Gordon Syndrome: a continuing story". Pediatric Nephrology (Berlin, Germany) 30 (11): 1903–1908. doi:10.1007/s00467-014-2956-7. ISSN 1432-198X. PMID 25503323.
- ↑ Garovic, Vesna D. (2006). "Monogenic Forms of Low-Renin Hypertension". Nature Clinical Practice. Nephrology (Nature Clinical Practice Nephrology) 2 (11): 624–30. doi:10.1038/ncpneph0309. PMID 17066054. https://www.medscape.com/viewarticle/547662_8. Retrieved 18 October 2019.
- ↑ "Clinical improvement in patients with autosomal recessive pseudohypoaldosteronism and the necessity for salt supplementation.". Clinical and Experimental Nephrology 14 (5): 518–519. 2010. doi:10.1007/s10157-010-0326-8. PMID 20661616.
- ↑ Pseudohypoaldosteronism at the US National Library of Medicine Medical Subject Headings (MeSH)
- ↑ CHEEK DB, PERRY JW (1958). "A salt wasting syndrome in infancy.". Arch Dis Child 33 (169): 252–6. doi:10.1136/adc.33.169.252. PMID 13545877.
- ↑ "Type I pseudohypoaldosteronism includes two clinically and genetically distinct entities with either renal or multiple target organ defects". The Journal of Clinical Endocrinology and Metabolism 73 (5): 936–44. Nov 1991. doi:10.1210/jcem-73-5-936. PMID 1939532. https://zenodo.org/record/890914.
- ↑ "Epithelial sodium channel (ENaC) family: Phylogeny, structure-function, tissue distribution, and associated inherited diseases.". Gene 579 (2): 95–132. Jan 2016. doi:10.1016/j.gene.2015.12.061. PMID 26772908.
- ↑ "Exclusion of the locus for autosomal recessive pseudohypoaldosteronism type 1 from the mineralocorticoid receptor gene region on human chromosome 4q by linkage analysis". J Clin Endocrinol Metab 80 (11): 3341–5. 1995. doi:10.1210/jcem.80.11.7593448. PMID 7593448. https://zenodo.org/record/890760.
- ↑ "Mutations in subunits of the epithelial sodium channel cause salt wasting with hyperkalaemic acidosis, pseudohypoaldosteronism type 1". Nat Genet 12 (3): 248–53. 1996. doi:10.1038/ng0396-248. PMID 8589714.
- ↑ "Expression of the epithelial sodium channel (ENaC) in the endometrium - Implications for fertility in a patient with pseudohypoaldosteronism". The Journal of Steroid Biochemistry and Molecular Biology 183: 137–141. October 2018. doi:10.1016/j.jsbmb.2018.06.007. PMID 29885352.
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