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SLC12A3
solute carrier family 12 member 3
The SLC12A3 gene encodes the sodium chloride co-transporter (NCC) protein, which is vital for kidney function, specifically in regulating salt reabsorption and maintaining fluid balance. SLC12A3 is a gene that plays a critical role in how the kidneys manage salt and water in the body.
SLC12A3 is located on the long (q) arm of chromosome 16, at band 16q13. Arm ratio per GRCh38 - banding schematic.
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Overview
The SLC12A3 gene, also known as solute carrier family 12 member 3, carries the genetic information for a protein called the sodium chloride co-transporter (NCC). This protein is essential for proper kidney function, specifically its role in reabsorbing salt into the bloodstream from filtered urine. The activity of NCC impacts the body's fluid retention and contributes to blood pressure regulation.
What the gene does
The SLC12A3 gene directs the production of the NCC protein, which functions as a sodium chloride co-transporter. This protein facilitates the movement of charged sodium (Na+) and chloride (Cl-) ions across cellular membranes. Within the renal system, the NCC protein is a key component responsible for retrieving sodium chloride (salt) from urine, returning it to circulation. The amount of salt reabsorbed by the kidneys directly influences fluid levels and blood pressure control. When the NCC protein's function is compromised, the kidneys may struggle to reabsorb salt efficiently, leading to imbalances in electrolytes and bodily fluids.
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Chromosome location
The SLC12A3 gene is situated on chromosome 16 at position 16q13. This specific region on the long arm (q) of chromosome 16 contains the genetic instructions necessary for producing the NCC protein. This gene is inherited in an autosomal recessive pattern.
Protein structure
The SLC12A3 gene encodes a protein composed of 1021 amino acids. This protein includes a key functional area known as the Scissor helix, located between amino acids 615 and 630. This and other structural elements contribute to the overall function of the NCC co-transporter protein.
Key variants
Genetic variations within the SLC12A3 gene can influence how the NCC protein functions. These genetic alterations can include changes to single amino acids, or insertions and deletions of genetic material. Such variants may impede the NCC protein's ability to reach the cell membrane correctly or reduce its efficiency in transporting sodium and chloride ions.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.1095+1G>C | - | Pathogenic/Likely pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.1703G>A | p.Trp568Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.1758G>A | p.Trp586Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.1992del | p.Phe665fs | Pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.2099T>C | p.Leu700Pro | Pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.2633+1G>C | - | Pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.2814del | p.Trp939fs | Pathogenic/Likely pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.841_842insA | p.Trp281Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.945del | p.Gly316fs | Pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
c.965-1_976delinsACCGAAAATTTT | - | Pathogenic | ★★☆☆ | Familial hypokalemia-hypomagnesemia |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Variants in the SLC12A3 gene are primarily linked to Gitelman syndrome. This inherited condition affects the kidneys' capacity to reabsorb salt, leading to electrolyte imbalances such as low potassium and magnesium levels, and elevated calcium in the urine. Numerous changes in the SLC12A3 gene have been identified in individuals with Gitelman syndrome. Most of these involve single amino acid alterations within the NCC co-transporter protein, which either prevent it from reaching the cell membrane or affect its functionality.
Inheritance pattern
Conditions caused by pathogenic SLC12A3 variants typically follow autosomal recessive inheritance.
When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.
UK clinical status
The SLC12A3 gene is recognised within the UK's NHS Genomic Medicine Service pathways. It is featured on several NHS Genomic Medicine Service national test directories via PanelApp, including panels for 'Likely inborn error of metabolism', 'Renal tubulopathies', and 'Undiagnosed metabolic disorders', all categorised as having strong evidence (green status).
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
Maintaining a healthy lifestyle, including a balanced diet and regular physical activity, generally supports overall kidney health. However, there is no conclusive evidence that specific lifestyle changes can prevent or cure conditions associated with SLC12A3 gene variants.
Supplement considerations
While electrolyte imbalances are a feature of Gitelman syndrome, individuals should consult a healthcare professional before taking any supplements, including those for potassium or magnesium. There is no conclusive evidence that supplements can prevent conditions associated with SLC12A3 gene variants.
Frequently asked questions
What is the main function of the SLC12A3 gene?
The SLC12A3 gene provides instructions for making the NCC protein, which is a sodium chloride co-transporter. This protein is crucial for the kidneys' ability to reabsorb salt from urine back into the bloodstream, helping to regulate fluid balance and blood pressure.
What condition is most commonly associated with changes in the SLC12A3 gene?
Variants in the SLC12A3 gene are most commonly associated with Gitelman syndrome. This is an inherited kidney disorder characterised by electrolyte imbalances due to impaired salt reabsorption.
How do variants in SLC12A3 affect kidney function?
Variants in SLC12A3 can disrupt the NCC protein's function. This can lead to the protein not reaching the cell membrane correctly or being unable to transport sodium and chloride ions effectively, thereby impairing the kidneys' ability to reabsorb salt.
References
- Lo YF, Nozu K, Iijima K. Recurrent deep intronic mutations in the SLC12A3 gene responsible for Gitelman's syndrome. Clinical journal of the American Society of Nephrology : CJASN. 2011. PMID: 21051746
- Aoi N, Nakayama T, Sato N. Case-control study of the role of the Gitelman's syndrome gene in essential hypertension. Endocrine journal. 2008. PMID: 18362449
- Ji W, Foo JN, O'Roak BJ. Rare independent mutations in renal salt handling genes contribute to blood pressure variation. Nature genetics. 2008. PMID: 18391953
- Riveira-Munoz E, Chang Q, Godefroid N. Transcriptional and functional analyses of SLC12A3 mutations: new clues for the pathogenesis of Gitelman syndrome. Journal of the American Society of Nephrology : JASN. 2007. PMID: 17329572
- Sabath E, Meade P, Berkman J. Pathophysiology of functional mutations of the thiazide-sensitive Na-Cl cotransporter in Gitelman disease. American journal of physiology. Renal physiology. 2004. PMID: 15068971
- De Jong JC, Van Der Vliet WA, Van Den Heuvel LP. Functional expression of mutations in the human NaCl cotransporter: evidence for impaired routing mechanisms in Gitelman's syndrome. Journal of the American Society of Nephrology : JASN. 2002. PMID: 12039972
- Cruz DN, Simon DB, Nelson-Williams C. Mutations in the Na-Cl cotransporter reduce blood pressure in humans. Hypertension (Dallas, Tex. : 1979). 2001. PMID: 11408395
- Lemmink HH, Knoers NV, Károlyi L. Novel mutations in the thiazide-sensitive NaCl cotransporter gene in patients with Gitelman syndrome with predominant localization to the C-terminal domain. Kidney international. 1998. PMID: 9734597
- Simon DB, Nelson-Williams C, Bia MJ. Gitelman's variant of Bartter's syndrome, inherited hypokalaemic alkalosis, is caused by mutations in the thiazide-sensitive Na-Cl cotransporter. Nature genetics. 1996. PMID: 8528245
- Mastroianni N, De Fusco M, Zollo M. Molecular cloning, expression pattern, and chromosomal localization of the human Na-Cl thiazide-sensitive cotransporter (SLC12A3). Genomics. 1996. PMID: 8812482