SCNN1B or SCNN1G genes and is inherited in an autosomal dominant manner. Treatment may include a low sodium diet and potassium-sparing diuretics to reduce blood pressure and normalize potassium levels. Conventional anti-hypertensive therapies are not effective.

Liddle syndrome is primarily characterized by severe, early-onset hypertension (high blood pressure). Although the condition may not be associated with any signs and symptoms initially, untreated hypertension can eventually lead to heart disease and stroke. Affected people may also have hypokalemia (low blood potassium) and metabolic alkalosis. Symptoms of hypokalemia can include weakness, fatigue, muscle pain (myalgia), constipation or heart palpitations. In most cases, the condition becomes apparent at a young age but some affected people are not diagnosed until well into adulthood.

SCNN1B orSCNN1G gene. Each of theses genes provides instructions for making one piece of a protein complex called the epithelial sodium channel (ENaC). These channels are found on the surface of certain cells (epithelial cells) throughout the body, including the kidneys, lungs, and sweat glands. The ENaC channel transports sodium into cells.

Mutations in the SCNN1B and SCNN1G genes affect an important region of the protein involved in signaling for its breakdown (degradation). As a result of the mutations, the protein is not tagged for degradation when it is no longer needed, and more ENaC channels remain at the cell's surface. The increase in channels at the cell surface abnormally increases the reabsorption of sodium, which leads to hypertension. Because removal of potassium from the blood is linked with reabsorption of sodium, excess sodium reabsorption leads to hypokalemia.

Liddle syndrome is inherited in an autosomal dominant manner. This means that to be affected, a person only needs a change (mutation) in one copy of the responsible gene in each cell. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family. A person with Liddle syndrome has a 50% chance with each pregnancy of passing along the altered gene to his or her child.

Treatment for Liddle syndrome consists of following a low sodium diet and taking potassium-sparing diuretics, which reduce blood pressure and correct hypokalemia and metabolic alkalosis. Conventional anti-hypertensive therapies are not effective for this condition.

With treatment, the long-term outlook (prognosis) for people with Liddle syndrome is good. However, untreated hypertension may lead to stroke, heart disease and/or kidney problems which can be fatal.