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Bartter syndrome


Other Names for this Disease

  • Bartter's syndrome
  • Hypokalemic alkalosis with hypercalciuria
  • Potassium wasting
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Overview

What is Bartter syndrome?

What are the signs and symptoms of Bartter syndrome?

What causes Bartter syndrome?

How is Bartter syndrome inherited?

Is genetic testing available for Bartter syndrome?

How is Bartter syndrome diagnosed?

How might Bartter syndrome be treated?

What is the long term outlook for people Bartter syndrome?

What is Bartter syndrome?

Bartter syndrome is a group of similar kidney disorders that cause an imbalance of potassium, sodium, chloride, and other molecules in the body. In some cases, the condition manifests before birth with increased amniotic fluid surrounding the affected fetus (polyhydramnios). Affected infants typically do not grow and gain wait as expected. Dehydration, constipation and increased urine production result from losing too much salt (sodium chloride) in the urine, and weakening of the bones can occur due to excess loss of calcium. Low levels of potassium in the blood (hypokalemia) can cause muscle weakness, cramping, and fatigue.[1] It is caused by mutations in any one of at least 5 genes and is inherited in an autosomal recessive manner.[2] The different types of Bartter syndrome are classified according to the specific gene that causes the condition.[1] Treatment depends on the type of the syndrome present but chiefly focuses on preventing the loss of too much potassium from the body.[3]
Last updated: 11/7/2011

What are the signs and symptoms of Bartter syndrome?

The signs and symptoms associated with Bartter syndrome can vary depending on the form of Bartter syndrome an affected individual has.[3] The antenatal forms (beginning before birth) can be life-threatening, while the classical form, beginning in early childhood, tends to be less severe.[1]

The antenatal forms of Bartter syndrome (types I, II and IV) may first be characterized by abnormally high levels of amniotic fluid surrounding the affected fetus (polyhydramnios); premature delivery; and possibly life-threatening salt (sodium-chloride) loss.[4] Affected newborns may have fever, vomiting, diarrhea, failure to thrive, delayed growth, intellectual disability, and/or distinctive facial features (triangular face, prominent forehead, large eyes, protruding ears, and drooping mouth).[3] Individuals with type IV may also have sensorineural deafness (hearing loss caused by abnormalities in the inner ear).[1]

Classical Bartter syndrome typically becomes apparent in infancy and is characterized by failure to thrive and constipation in the first year of life.[4] Symptoms may include salt craving, fatigue, muscle weakness, growth delay and developmental delay.[3]

Loss of excess sodium chloride through the urine can lead to dehydration, constipation, and increased urine production (polyuria). Loss of excess calcium through the urine (hypercalciuria) can cause weakening of the bones (osteopenia). When this excess calcium becomes deposited in the kidneys, tissue in the kidneys can become hardened (nephrocalcinosis). Low levels of potassium in the blood (hypokalemia) cause the muscle weakness, cramping, and fatigue in affected individuals.[2]
Last updated: 11/7/2011

What causes Bartter syndrome?

Bartter syndrome may be caused by mutations in any one of several genes; the genetic cause in each case corresponds to the type of Bartter syndrome each affected individual has. Types I, II and IV typically result in the antenatal forms of Bartter syndrome (beginning before birth) while type III results in classical Bartter syndrome (usually beginning in early childhood). Type I results from mutations in the SLC12A1 gene; type II from mutations in the KCNJ1 gene; type III from mutations in the CLCNKB gene; and type IV from mutations in the BSND gene, or from a combination of mutations in the CLCNKA and CLCNKB genes. In some people with Bartter syndrome, the genetic cause of the disorder remains unknown; there may be other genes that cause the condition that have not yet been identified.[2]

All of these genes are essential for normal kidney function - they are involved in the kidneys' abilities to reabsorb salt. Abnormal changes in these genes impair these abilities, allowing for the loss of excess salt through the urine and also affecting the reabsorption of other things including potassium and calcium. The resulting imbalance of these in the body lead to the signs and symptoms of Bartter syndrome.[2]
Last updated: 11/7/2011

How is Bartter syndrome inherited?

Bartter syndrome is inherited in an autosomal recessive manner, which means that both copies of the disease-causing gene (one inherited from each parent) have a mutation in an affected individual. Parents who each carry one mutated copy of the gene are referred to as carriers and typically do not have signs or symptoms of the condition. When two carriers for an autosomal recessive condition have children, each child has a 25% (1 in 4) risk to have the condition, a 50% (1 in 2) risk to be a carrier like each of the parents, and a 25% chance to not have the condition and not be a carrier.

Click here to visit the Genetic Home Reference Web site and view an illustration that demonstrates autosomal recessive inheritance.
Last updated: 12/5/2011

Is genetic testing available for Bartter syndrome?

Yes, genetic testing for Bartter syndrome is available. GeneTests lists the names of laboratories that are performing clinical genetic testing for Bartter syndrome. To view a list of the clinical laboratories performing testing for each type of Bartter syndrome, click on the appropriate link below:

Please note that most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, individuals interested in learning more will need to work with a health care provider or a genetics professional.

Last updated: 11/7/2011

How is Bartter syndrome diagnosed?

Bartter syndrome is usually diagnosed after a combination of tests are performed on an individual with the signs and symptoms of the condition. Blood test results in an affected individual typically show low blood potassium levels (with normal blood pressure); low blood chloride levels; and an acid/base balance that is skewed towards the base (i.e. the blood is more alkaline than usual). High levels of the hormones renin and aldosterone in the blood would also support the diagnosis. Urine test results that would support the diagnosis include high levels of potassium and chloride, suggesting that the kidneys have impaired ability to control the concentrations of these electrolytes.[3] A positive genetic test result would confirm the diagnosis.
Last updated: 11/7/2011

How might Bartter syndrome be treated?

Treatment of Bartter syndrome depends on the type of the syndrome that the affected individual has, but it primarily focuses on preventing the loss of too much of potassium from the body.[3] This may include oral potassium (K) supplements, medication such as indomethacin, and potassium-sparing diuretics. In high-stress situations such as illness or trauma, blood electrolyte levels can change rapidly, which may require immediate intravenous treatment.[2] Genetic counseling may benefit affected individuals and their families.[3]

eMedicine has an article containing additional, thorough information about the management and treatment of Bartter syndrome. Click here to view this information.
Last updated: 11/7/2011

What is the long term outlook for people Bartter syndrome?

Currently there is no cure for Bartter syndrome, but treatments are available. Severity of symptoms (and associated complications) vary from person to person. People with Bartter syndrome must take medications consistently, as prescribed. They also must be careful to maintain an adequate fluid and electrolyte balance. With treatment, prognosis in many cases is good. Treated individuals with Bartter syndrome are often able to lead fairly normal lives.[5]
Last updated: 12/7/2011

References
  1. Bartter syndrome. Genetics Home Reference. February 2011; http://ghr.nlm.nih.gov/condition/bartter-syndrome. Accessed 11/5/2011.
  2. G. Colussi. Bartter syndrome. Orphanet. July 2007; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=112. Accessed 11/5/2011.
  3. Bartter's syndrome. NORD. September 23, 2007; http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/589/viewAbstract. Accessed 11/5/2011.
  4. Proesmans W. Threading through the mizmaze of Bartter syndrome. Pediatric Nephrology. July 2006; 21(7):896-902.
  5. Frassetto LA et al.,. Bartter syndrome: Follow-up. MedScape. 2009; http://emedicine.medscape.com/article/238670-followup#a2651. Accessed 12/7/2011.


Other Names for this Disease
  • Bartter's syndrome
  • Hypokalemic alkalosis with hypercalciuria
  • Potassium wasting
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.