Liddle's syndrome

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Liddle's syndrome
Synonyms	Pseudoaldosteronism
Pronounce
Specialty	Nephrology
Symptoms	Hypertension, hypokalemia, metabolic alkalosis
Complications	N/A
Onset	Childhood or early adulthood
Duration	Lifelong
Types	N/A
Causes	Genetic mutation in the SCNN1B or SCNN1G genes
Risks	Family history of the condition
Diagnosis	Genetic testing, blood pressure measurement, electrolyte levels
Differential diagnosis	Hyperaldosteronism, Cushing's syndrome, Gordon's syndrome
Prevention	N/A
Treatment	Amiloride, triamterene
Medication	Potassium-sparing diuretics
Prognosis	Good with treatment
Frequency	Rare
Deaths	Rare, if untreated

Liddle's syndrome is a rare genetic disorder characterized by hypertension (high blood pressure) and hypokalemia (low blood potassium levels) due to a defect in the renal tubules of the kidney. It is an autosomal dominant condition, meaning that only one copy of the mutated gene is necessary for the disorder to be expressed.

Pathophysiology

Diagram of autosomal dominant inheritance

Liddle's syndrome is caused by mutations in the genes encoding the epithelial sodium channel (ENaC) subunits, which are located on the chromosome 16p12. These mutations lead to increased activity of the sodium channels in the collecting ducts of the kidney, resulting in excessive reabsorption of sodium and water, and increased excretion of potassium. This sodium retention leads to volume expansion and hypertension.

Clinical Features

Patients with Liddle's syndrome typically present with early-onset hypertension, often in childhood or early adulthood. The hypertension is often severe and resistant to standard antihypertensive treatments. Hypokalemia is another common feature, which can lead to muscle weakness, fatigue, and cardiac arrhythmias.

Diagnosis

The diagnosis of Liddle's syndrome is based on clinical features, family history, and laboratory findings. Genetic testing can confirm the presence of mutations in the ENaC genes. Laboratory tests typically show low plasma renin activity and low aldosterone levels, despite the presence of hypertension.

Treatment

The treatment of Liddle's syndrome involves the use of potassium-sparing diuretics such as amiloride or triamterene, which directly inhibit the ENaC channels, thereby reducing sodium reabsorption and correcting the hypokalemia. Standard antihypertensive medications are often ineffective.

Prognosis

With appropriate treatment, individuals with Liddle's syndrome can manage their blood pressure and potassium levels effectively, reducing the risk of complications such as stroke and heart disease.

See also

• Hypertension
• Hypokalemia
• Genetic disorders
• Renal physiology