Liddle's syndrome

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Liddle's syndrome Classification and external resources
OMIM	177200
DiseasesDB	7471

Liddle's Syndrome is an autosomal dominant disorder that mimics hyperaldosteronism. It involves problems with excess resorption of sodium and loss of potassium from the renal tubule. Hypertension begins at a very early age, often in infancy.

1 Etiology
2 Signs & Symptoms
3 Diagnosis
4 Treatment

[edit] Etiology

This syndrome is caused by dysregulation of an epithelial Na+ channel (ENaC) due to a genetic mutation at the 16p12-p13 locus. The mutation changes a domain in the channel so it is no longer degraded correctly by the Ubiquitin Proteasome system. Specifically the PY motif in the protein is deleted or altered so the E3 ligase (Nedd4) no longer recognizes the channel.

Liddle's Syndrome is inherited in an autosomal dominant fashion.

[edit] Signs & Symptoms

Children with Liddle's syndrome are frequently asymptomatic. The first indication of the disease is often the incidental finding of hypertension during a routine physical exam. This syndrome is rare and may only be considered by the treating physician after the child's hypertension is found to be recalcitrant to antihypertensive agents.

[edit] Diagnosis

Evaluation of the pediatric hypertensive patient usually involves analysis of blood electrolytes and an aldosterone level, as well as other tests. In Liddle's disease, the serum sodium is elevated and the serum potassium is low. These two findings are also found in hyperaldosteronism, another rare cause of pediatric hypertension. Primary hyperaldosteronism (also known as Conn's syndrome), is due to an aldosterone-secreting adrenal tumor or adrenal hyperplasia. Aldosterone levels are high in hyperaldosteronism, whereas they are low to normal in Liddle's syndrome.

[edit] Treatment

The treatment is with a potassium-sparing diuretic that directly blocks the sodium channel, such as amiloride or triamterene. Note that spironolactone (another potassium-sparing diuretic) is not used, as it is an aldosterone antagonist and Liddle's syndrome is not affected by aldosterone regulation.