Bartter syndrome is a group of very similar kidney disorders that cause an imbalance of potassium, sodium, chloride, and related molecules in the body. In some cases, Bartter syndrome becomes apparent before birth. The disorder can cause polyhydramnios, which increases the risk of premature birth. Beginning in infancy, affected individuals often fail to grow and gain weight at the expected rate. They lose excess amounts of salt in their urine, which leads to dehydration, constipation, and increased urine production. In addition, large amounts of calcium are lost through the urine, which can cause weakening of the bones. Some of the calcium is deposited in the kidneys as they are concentrating urine, leading to hardening of the kidney tissue. Bartter syndrome is also characterized by low levels of potassium in the blood, which can result in muscle weakness, cramping, and fatigue. Rarely, affected children develop hearing loss caused by abnormalities in the inner ear.
Two major forms of Bartter syndrome are distinguished by their age of onset and severity. One form begins before birth (antenatal) and is often life-threatening. The other form, often called the classical form, begins in early childhood and tends to be less severe. Once the genetic causes of Bartter syndrome were identified, researchers also split the disorder into different types based on the genes involved.
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. The genes associated with Bartter syndrome play important roles in normal kidney function. The proteins produced from these genes are involved in the kidneys' reabsorption of salt. Mutations in any of the genes impair the kidneys' ability to reabsorb salt, leading to the loss of excess salt in the urine. Abnormalities of salt transport also affect the reabsorption of other charged atoms, including potassium and calcium. The resulting imbalance of ions in the body leads to the major features of Bartter syndrome.
We provide testing for Bartters syndrome Type 1 and Type 2 .
Neonatal Bartter's syndrome Type 1
The NCC2 protein mediates active reabsorption of sodium chloride in the thick ascending limb of the loop of Henle and represents the site of action of furosemide and bumetanide. Mutations of SLC12A1 impair this process.
Neonatal Bartter's syndrome Type 2
||ROMK protein is encoded by the KCNJ1 gene. ROMK is an integral membrane protein in the potassium channel. It is activated by internal ATP and plays an important role in potassium homeostasis. The encoded protein allows potassium to flow into a cell rather than out of a cell. Mutations in KCNJ1 can interrupt this process.
Purpose: Confirmation of Clinical Diagnosis
Methodology: Sequencing of entire coding region
Test Requisition: Sequencing Requisition
Specimen Requirements: 2-5 mL Blood- Lavender Top Tube
Type 1 SLCA12A1 CPT Code: 81407 Cost: $750.00
Type 2 KCNJ1 CPT Code: 81404 Cost: $750.00
Panel CPT Code: 81404, 81407 Cost: $1500.00 (Oklahoma Medicaid requires preauthorization for this test)
Turn-around-time: 4 weeks
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5. Proesmans W (2006). "Threading through the mizmaze of Bartter syndrome". Pediatr. Nephrol. 21 (7): 896–902