Liddle syndrome

Liddle syndrome is a rare disorder in which too much salt is retained from the urine due to a defect in the kidney tubules. As a result, too much salt is retained in the body. Liddle syndrome is caused by a defect (mutation) in the genetic material (DNA). Due to such a mutation, specific cells in the renal tubules will retain too much salt. Such a problem may be caused by a mutationof the SNCC1b  or SCNN1g gene on chromosome 16p12. These genes are responsible for the production of the salt channel ENaC (epithelial sodium channel) in the collecting tube of the kidney.

Signs and symptoms
A mutation in either SNCC1B or SCNN1G results in a disorder in which the kidney absorbs too much salt. Too much salt retention leads to a high blood pressure. Most patients already present at young age with a high blood pressure. Often, this is also accompanied by a low potassium.
Inheritance
Liddle syndrome is a hereditary disease, which is inherited autosomal dominant. This means that a person gets this condition if he or she has a mutation in one SNCC1b- or SCNN1g- gene. A son or daughter of someone with the disease has a chance of 50% to inherit the mutation.

Diagnosis
The diagnosis is suspected if a person has the combination of a high blood pressure and a low potassium content, accompanied by low concentrations of certain hormones in the blood. The diagnosis can be confirmed by a genetic test wherein the DNA mutation can be demonstrated.

Treatment
There is no causal treatment available to treat the underlying disorder. In other words, the underlying problem (the dysfunctional ENaC channel) cannot be remedied. However, the activity of ENaC can be inhibited by treatment with drugs such as amiloride or triamterene.

Prognosis
Liddle syndrome is a chronic condition, persisting for life. The prognosis of patients with Liddle syndrome is good, as long the hypertension is treated well.