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CLCNKB gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CLCNKB gene

The CLCNKB gene provides instructions for a chloride channel that regulates salt reabsorption in the kidneys and supports normal hearing function in the inner ear.

Normal Function

The CLCNKB gene belongs to the CLC family of genes, which provide instructions for making chloride channels. These channels transport negatively charged chloride ions and play a key role in a cell's ability to generate and transmit electrical signals.

The CLCNKB gene provides instructions for making a chloride channel called ClC-Kb. These channels are found predominantly in the kidneys. ClC-Kb is one of several proteins that work together to regulate the movement of ions into and out of kidney cells. The transport of chloride ions by ClC-Kb channels is part of the mechanism by which the kidneys reabsorb salt (sodium chloride or NaCl) from the urine back into the bloodstream. The retention of salt affects the body's fluid levels and helps maintain blood pressure.

ClC-Kb channels are also located in the inner ear, where they play a role in normal hearing.

Health Conditions Related to Genetic Changes

Bartter syndrome

More than 30 mutations in the CLCNKB gene have been identified in people with Bartter syndrome type III, also described as classical Bartter syndrome. A loss of functional ClC-Kb channels impairs the transport of chloride ions in the kidneys, causing the kidneys to lose excess salt through the urine (salt wasting). This imbalance underlies many of the major features of Bartter syndrome type III.

A combination of CLCNKA and CLCNKB gene mutations causes a life-threatening form of the disorder known as Bartter syndrome type IV or antenatal Bartter syndrome with sensorineural deafness. In addition to salt wasting, this form is characterized by hearing loss resulting from a loss of ClC-Ka and ClC-Kb function in the inner ear.

Gitelman syndrome

Mutations in the CLCNKB gene are a rare cause of Gitelman syndrome. These genetic changes impair the kidneys' ability to reabsorb salt, leading to salt wasting. Abnormalities of salt transport also affect the reabsorption of other ions, including potassium, magnesium, and calcium, leading to the characteristic features of Gitelman syndrome.

Other disorders

A common variation (polymorphism) in the CLCNKB gene, where the amino acid threonine is replaced by serine at position 481 (Thr481Ser or T481S), has been associated with salt-sensitive hypertension. This genetic change increases the activity of the ClC-Kb channel, directing the kidneys to reabsorb more salt into the bloodstream, which raises blood pressure.

Other Names for This Gene

  • chloride channel Kb
  • chloride channel protein ClC-Kb
  • chloride channel, kidney, B
  • chloride channel, voltage-sensitive Kb
  • ClC-K2
  • ClC-Kb
  • CLCKB
  • CLCKB_HUMAN
  • hClC-Kb

Frequently Asked Questions

First‑line therapy includes potassium‑sparing diuretics (spironolactone or eplerenone) to conserve potassium, and NSAIDs such as indomethacin to blunt prostaglandin‑driven salt loss. In some patients, a thiazide‑type diuretic is added cautiously to reduce calcium excretion. Close monitoring guides dose adjustments to avoid hyperkalemia or renal impairment.
Diagnosis combines clinical findings (hypokalemia, metabolic alkalosis, polyuria, growth delay) with laboratory tests showing elevated renin and aldosterone, plus genetic testing that identifies pathogenic variants in CLCNKB. A renal ultrasound may show normal or mildly enlarged kidneys, helping to differentiate it from other tubulopathies.
Isolated CLCNKB mutations rarely cause hearing loss; the inner‑ear expression of ClC‑Kb is less critical than ClC‑Ka. Sensorineural deafness is typically seen when both CLCNKA and CLCNKB are mutated (Bartter type IV).
diet enriched in sodium (e.g., adding a pinch of salt to meals, using electrolyte‑rich broths) and potassium (bananas, oranges, leafy greens) is often advised. Limiting foods that increase urinary calcium loss, such as excessive caffeine or high‑oxalate foods, can also reduce stone risk. Fluid intake should be adequate to prevent dehydration, but not excessive if polyuria is severe.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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