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

BSND gene

The BSND gene provides instructions for making the protein barttin, which is essential for kidney function and hearing.

Normal Function

The BSND gene provides instructions for making a protein called barttin. This protein is found primarily in the kidneys, where it attaches (binds) to two specific chloride channels: ClC-Ka (produced from the CLCNKA gene) and ClC-Kb (produced from the CLCNKB gene). The ClC-Ka and ClC-Kb channels transport charged atoms of chlorine (chloride ions) out of kidney cells.

Barttin is essential for the normal placement of ClC-Ka and ClC-Kb channels in the cell membrane. It also regulates the channels' stability and function. The transport of chloride ions 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.

Barttin, ClC-Ka, and ClC-Kb are also found in the inner ear, where they play a role in normal hearing.

Health Conditions Related to Genetic Changes

Bartter syndrome

More than a dozen mutations in the BSND gene have been identified in people with Bartter syndrome type IV. This form of the disorder causes severe or life-threatening health problems that become apparent before or soon after birth. Affected individuals also have hearing loss caused by abnormalities in the inner ear, which is why Bartter syndrome type IV is also known as antenatal Bartter syndrome with sensorineural deafness.

BSND gene mutations impair barttin's ability to regulate the ClC-Ka and ClC-Kb channels. Some mutations keep the channels from ever reaching the cell membrane. Other mutations allow the channels to reach the cell membrane but prevent them from transporting ions properly. As a result, the kidneys cannot reabsorb salt normally and excess salt is lost through the urine (salt wasting). The abnormal salt loss disrupts the normal balance of ions in the body. This imbalance underlies many of the major features of Bartter syndrome, including:

  • Failure to grow and gain weight at the expected rate (failure to thrive)
  • Dehydration
  • Constipation
  • Increased urine production (polyuria)

A loss of ClC-Ka and ClC-Kb function in the inner ear is responsible for the hearing loss characteristic of Bartter syndrome type IV.

Nonsyndromic hearing loss

MedlinePlus Genetics provides information about Nonsyndromic hearing loss.

Frequently Asked Questions

Prenatal signs often include severe polyhydramnios (excess amniotic fluid) beginning in the second trimester, caused by fetal polyuria. After birth, infants present with extreme dehydration, profound loss of sodium and potassium in urine, metabolic alkalosis, failure to thrive, and congenital sensorineural hearing loss discovered during newborn hearing screening. Confirmation is made through biochemical evaluation and genetic testing of the BSND gene.
Bartter syndrome type IV is inherited in an autosomal recessive pattern. Both parents are typically asymptomatic carriers who each carry one mutated copy of the BSND gene. For each subsequent pregnancy between carrier parents, there is a 25 percent chance of having an affected child, a 50 percent chance of having an asymptomatic carrier child, and a 25 percent chance of having a completely unaffected child.
Daily care focuses on preventing life-threatening dehydration and electrolyte imbalances. Management involves liberal fluid intake, targeted oral sodium chloride and potassium chloride supplementation, and frequently the use of nonsteroidal anti-inflammatory drugs like indomethacin to suppress prostaglandin production and reduce renal salt wasting. Frequent blood and urine electrolyte monitoring is mandatory.
Medical therapy for the kidneys does not improve hearing because the BSND gene product, barttin, is required for endolymph fluid homeostasis inside the inner ear. However, the hearing loss is non-progressive and can be effectively managed with conventional hearing aids or early cochlear implantation, which supports normal language development.
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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