Bartter syndrome type 2

Bartter syndrome type 2 (also known as neonatal Bartter syndrome type 2 or ROMK-related Bartter syndrome) is a rare inherited kidney disorder caused by mutations in the KCNJ1 gene, which encodes the renal outer medullary potassium channel (ROMK). This channel plays a critical role in potassium recycling in the thick ascending limb of the loop of Henle and in potassium secretion in the collecting duct of the kidney. Loss of ROMK function impairs sodium chloride reabsorption, leading to severe salt wasting, hypokalemic metabolic alkalosis, and secondary hyperaldosteronism. Bartter syndrome type 2 typically presents in the antenatal or neonatal period. During pregnancy, affected fetuses often cause maternal polyhydramnios due to excessive fetal urine production. After birth, affected infants present with polyuria, polydipsia, dehydration, failure to thrive, and electrolyte imbalances including hypokalemia, hypochloremic metabolic alkalosis, and elevated renin and aldosterone levels. Hypercalciuria and nephrocalcinosis are frequently observed. A distinctive feature of Bartter syndrome type 2 is that some patients may initially present with transient hyperkalemia in the neonatal period before developing the characteristic hypokalemia, which reflects the role of ROMK in potassium secretion in the collecting duct. Treatment is supportive and aimed at correcting electrolyte and fluid imbalances. This includes aggressive fluid and electrolyte replacement, potassium supplementation, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as indomethacin, which help reduce renal prostaglandin production and improve electrolyte balance. Potassium-sparing diuretics may also be used. With appropriate management, many patients can achieve improved growth and quality of life, though lifelong monitoring and treatment are required. There is currently no cure for Bartter syndrome type 2.

Common questions about Bartter syndrome type 2