Barter Syndrome classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Tayyaba Ali, M.D.[2]
Overview
Classification
- Bartter Syndrome can be classified into five different types based on genotype. Bartter syndrome can result from homozygous or mixed heterozygous mutations in any of the genes. Thus, affecting the function of genes responsible for synthesis or membrane insertion of the transporters in the ascending limb of the loop of Henle.[1][2][3][4][5]
- Bartter Syndrome type 1
- Mutation in NKCC2 gene results in impairment of sodium-potassium-chloride cotransporter (Na-K-2Cl) in the apical membrane.[1]
- Bartter Syndrome type 2
- Mutation in ROMK gene results in defective functioning of the luminal potassium channel.[2][3]
- Bartter Syndrome type 3
- Mutation in the ClC-Kb gene results in impairment of the basolateral chloride channel.[4][5]
- Type 3 is a severe salt-losing tubulopathy that develops when ClCKB becomes nonfunctional. ClCKB is a key determinant of tubular reabsorption of chloride and electrolytes along the distal tubule.
- Bartter Syndrome type 4
- Type IV results from the loss-of-function mutations in gene encoding barttin.
- Defects that reduce the activity of both ClC-Ka and ClC-Kb cause Bartter syndrome associated with sensorineural deafness (types IV and IVb).[6]
- Bartter Syndrome type 5
- Type 5 Bartter syndrome results from a gain-of-function mutation in the Ca-sensing receptor (CaSR).
- A gain-of-function mutation in CaSR in the basolateral membrane of the thick ascending limb enhances the function of this receptor. This results in hypocalcemia and impairs sodium chloride transport.
- Initially, type V Bartter syndrome referred to autosomal dominant hypocalcemia (also called autosomal dominant hypoparathyroidism).
| Disorder | Gene affected | Gene product | Clinical presentation (phenotype) |
|---|---|---|---|
| Bartter syndrome type I | SLC12A1 | NKCC2 | Antenatal Bartter syndrome (hyperprostaglandin E syndrome) |
| Bartter syndrome type II | KCNJ1 | ROMK | Antenatal Bartter syndrome |
| Bartter syndrome type III | ClC-Kb | CLC-Kb | Hypochloremia, mild hypomagnesemia, failure to thrive in infancy |
| Bartter syndrome type IVA | BSND | Barttin (B-subunit of CLC-Ka and CLC-Kb) | Antenatal Bartter syndrome (hyperprostaglandin E syndrome) and sensorineural deafness |
| Bartter syndrome type IVB | ClC-Ka and ClC-Kb | CLC-Ka and CLC-Kb | Antenatal Bartter syndrome (hyperprostaglandin E syndrome) and sensorineural deafness |
| Bartter syndrome type V | CaSR gene | CaSR | Bartter syndrome with hypocalcemia |
- Bartter syndrome types 1, 2, and 4 present at a younger age. They present with symptoms, often quite severe in the neonatal period.
- Bartter Syndrome type 3 also called classic Bartter syndrome present later in life and maybe sporadically asymptomatic or mildly symptomatic.[7]
References
- ↑ 1.0 1.1 Simon DB, Karet FE, Hamdan JM, DiPietro A, Sanjad SA, Lifton RP (1996). "Bartter's syndrome, hypokalaemic alkalosis with hypercalciuria, is caused by mutations in the Na-K-2Cl cotransporter NKCC2". Nat Genet. 13 (2): 183–8. doi:10.1038/ng0696-183. PMID 8640224.
- ↑ 2.0 2.1 Simon DB, Karet FE, Rodriguez-Soriano J, Hamdan JH, DiPietro A, Trachtman H; et al. (1996). "Genetic heterogeneity of Bartter's syndrome revealed by mutations in the K+ channel, ROMK". Nat Genet. 14 (2): 152–6. doi:10.1038/ng1096-152. PMID 8841184.
- ↑ 3.0 3.1 Lorenz JN, Baird NR, Judd LM, Noonan WT, Andringa A, Doetschman T; et al. (2002). "Impaired renal NaCl absorption in mice lacking the ROMK potassium channel, a model for type II Bartter's syndrome". J Biol Chem. 277 (40): 37871–80. doi:10.1074/jbc.M205627200. PMID 12122007.
- ↑ 4.0 4.1 Simon DB, Bindra RS, Mansfield TA, Nelson-Williams C, Mendonca E, Stone R; et al. (1997). "Mutations in the chloride channel gene, CLCNKB, cause Bartter's syndrome type III". Nat Genet. 17 (2): 171–8. doi:10.1038/ng1097-171. PMID 9326936.
- ↑ 5.0 5.1 Konrad M, Vollmer M, Lemmink HH, van den Heuvel LP, Jeck N, Vargas-Poussou R; et al. (2000). "Mutations in the chloride channel gene CLCNKB as a cause of classic Bartter syndrome". J Am Soc Nephrol. 11 (8): 1449–59. PMID 10906158.
- ↑ Krämer BK, Bergler T, Stoelcker B, Waldegger S (2008). "Mechanisms of Disease: the kidney-specific chloride channels ClCKA and ClCKB, the Barttin subunit, and their clinical relevance". Nat Clin Pract Nephrol. 4 (1): 38–46. doi:10.1038/ncpneph0689. PMID 18094726.
- ↑ Fremont OT, Chan JC (2012). "Understanding Bartter syndrome and Gitelman syndrome". World J Pediatr. 8 (1): 25–30. doi:10.1007/s12519-012-0333-9. PMID 22282380.