Sitosterolemia

The sitosterolemia is a rare congenital lipid metabolism disorder in which there is accumulation of phytosterols in various tissues of the body. The disease is one of the rare diseases ( orphan diseases ).

Pathology

Only a small proportion of ingested with food of plant sterols (phytosterols ) is absorbed in the digestive tract. Usually these phytosterols, including sitosterol, stigmasterol and campesterol, are largely excreted via the ABC transporters ABCG5 and ABCG8 back into the intestinal lumen. Through this mechanism, the uptake of exogenous phytosterols from the intestine is limited. The low proportion of phytosterols, which enters the blood is eliminated by the liver.

By autosomal recessive mutations in the coding for the ABC transporter genes excretion of phytosterols from the mucosal cells is reduced in the intestinal lumen. From unknown causes the excretion of phytosterols is reduced by the liver, as well as cholesterol biosynthesis. The blood plasma levels of sitosterol increases due to the elimination of strong disorder and promotes early atherosclerosis.

Clinical picture

In the context of lipid metabolism disorder it comes to the deposition of fat in the skin and the tendons ( xanthomas ). Furthermore, joint pain, arthritis and angina occur.

Epidemiology

The sitosterolemia is a rare disease ( orphan disease ). So far (as of November 2011) described 40 cases. The number of those affected is likely to be greater, especially as the disease can be misdiagnosed as hyperlipidemia.

Therapy

Treatment with ezetimibe reduces phytosterol levels. For this indication the drug is approved in the U.S. since 2002. A restrictive diet with greatly reduced intake of phytosterols may be indicated.

Forecast

At sitosterolemia ill persons a significantly increased risk of prematurely consequences of coronary heart disease (CHD) have to die as a heart attack.

History of Research

The disease was first described in 1974.