Liddle syndrome is characterized by the chronic high blood pressure (hypertension) beginning early in life which may present no signs and can go undiagnosed until adulthood. The functions of the kidneys are also to maintain the balance of salt and water in the body. Among individuals with this syndrome, the kidneys recover excess salt which increases the blood pressure and lowers the potassium level. In Liddle syndrome, the two hormones called the aldosterone and renin that are responsible for maintaining the balance of the salt in the kidneys are switched off. Therefore, measuring the level of these hormones can help with the diagnosis of Liddle syndrome. The exact prevalence of this rare condition is not known but it is evident among the populations globally.
Causes
This syndrome develops as the result of mutations in the gene SCNN1B or SCNN1G. These genes are responsible for the production of the subunit of a protein complex known as the epithelial sodium channel (ENaC) which is found in the epithelial cells of several tissues of the body including the kidneys. These channels are important for the transportation of sodium into cells. When the sodium levels become low in the blood, these channels open allowing the sodium to enter into cells. From the kidney cells, a process known as reabsorption is initiated when the sodium returns to the bloodstream rather than being excreted in the urine. The genetic changes alter the structure of the ENaC subunit and result in the abnormally increased reabsorption of sodium. The inheritance pattern is autosomal dominant manner meaning one copy of the defective gene in each cell can cause the disorder.
Symptoms
This syndrome is characterized by hypertension that can begin early and the low levels of potassium in the blood. Some of the symptoms of this condition include low abdominal bloating, constipation, fatigue, weakness, reduced aldosterone secretion, low blood potassium level, hypertension, shortness of breath and muscle weakness. In addition, they also exhibit metabolic acidosis where the blood pH can become low from the failure of the body to produce bicarbonate.
Diagnosis
The diagnosis is based on the analysis of the electrolytes in the blood and the level of aldosterone. Individuals affected with this syndrome present normally elevated serum sodium and low serum potassium. Further tests may be necessary to rule out other possible conditions such as hyperaldosteronism that can also cause hypertension among infants. The molecular genetic test can also identify the mutation in the gene responsible for causing this disorder.
Treatment
The treatment for this condition is focused on lowering the blood pressure and to prevent the complications that can develop from hypertension. Diuretics can block the sodium channel and stop the progression of the disease. It is also important that these affected individuals lower the salt content in their diet. People with this syndrome require the life-long treatment and regular medical evaluation.
References
http://rarerenal.org/patient-information/liddle-syndrome-patient-information/
https://ghr.nlm.nih.gov/condition/liddle-syndrome#statistics
