Genomic coordinate (human 11:128,838,020 KCNJ1) & (mouse 9:32,273,789 KCNJ1).
Cytoband (human 11q24.3 KCNJ1) & (mouse 9qA4 KCNJ1).
KCNJ1Here I present: “Bartter Syndrome”, Victor McKusick, Mendelian Inheritance in Man’, 1966. (KCNJ1) icd10=E26.81
Bartter syndrome is an inherited, autosomal recessive kidney disorder characterized by a defect in the thick ascending limb (TAL) of the loop of Henle, causing severe salt wasting, low blood pressure, high prostaglandin, hypokalemia, and metabolic alkalosis. It presents in infancy or childhod with polyuria, polydipsia, dehydration, and failure to thrive.
Key Aspects of Bartter Syndrome
Causes: Caused by genetic mutation (KCNJ1) that impair sodium, chloride, and potassium reabsorption in the kidneys.
Symptoms: Includes excessive urination, extreme thirst, muscle weakness/cramping, salt cravings, constipation, and characteristic facial features (triangular face, large eyes, prominent forehead).
Types & Prognosis:
Antenatal Bartter Syndrome (Types I, II, IV): Severe, presenting before birth with polyhydramnios and premature birth, often requiring intensive care.
Classical Bartter Syndrome (Type III): Less severe, presenting in early childhood with growth retardation and dehydration.
Prognosis: While not curable, it is manageable with medication; however, it can lead to chronic kidney disease or life-threatening electrolyte imbalances if untreated.
Treatment: Lifelong treatment involves replacing lost nutrients (potassium, magnesium, sodium) and using nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce prostaglandin levels.
It is important to distinguish this from Gitelman syndrome, which generally has a later onset and less severe symptoms.
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Anatomy: Extends from the inner/outer medulla junction to the cortex, ending at the macula densa.
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Function: Actively transports {Na}, {K} and {Cl} out of the lumen into the interstitium via the apical NKCC2 transporter and basolateral Na+/K+ATPase.
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Impermeability: The TAL is highly impermeable to water, which allows the luminal fluid to become diluted (hypo-osmotic) as it ascends.
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Medullary Gradient: By pumping salt into the medullary interstitium without water, it generates the osmotic gradient necessary for water reabsorption in the collecting duct.
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Clinical Relevance: Target for loop diuretics (furosemide), which inhibit the NKCC2 transporter, and site of Bartter syndrome.
- There is evidence that Bartter syndrome is caused by mutation in the potassium inwardly rectifying channel subfamily-J member-1 (KCNJ1) gene encoded on genomic coordinate 11:128,838,020 and cytoband 11q24.3 in humans.
