sitosterolemie

Sitosterolemia is a rare autosomal recessive genetic disorder that affects lipid metabolism. It is characterized by elevated levels of plant sterols, such as sitosterol and campesterol, in the blood and tissues. This condition is caused by mutations in the ABCG5 or ABCG8 genes, which are responsible for the ATP-binding cassette transporters G5 and G8. These transporters play a crucial role in mediating the efflux of dietary and biliary sterols from the intestinal enterocytes and hepatocytes back into the intestinal lumen.

Individuals with sitosterolemia typically present with symptoms related to the deposition of plant sterols in various tissues. The most prominent feature is the development of xanthomas, which are yellowish deposits of cholesterol and other lipids in the skin, tendons, and other soft tissues. These xanthomas can be particularly troublesome and may lead to joint pain and limited mobility. Cardiovascular disease is another significant complication, as the accumulation of plant sterols can contribute to the development of atherosclerosis, leading to an increased risk of heart attacks and strokes. Other symptoms may include premature jaundice, gallstones, and mild liver dysfunction.

The diagnosis of sitosterolemia is usually made based on clinical presentation and confirmed by laboratory tests. Blood tests will show significantly elevated levels of plant sterols, while cholesterol levels may be normal or only slightly elevated. Genetic testing can identify mutations in the ABCG5 or ABCG8 genes.

Treatment for sitosterolemia focuses on reducing the absorption of plant sterols and increasing their excretion. A low-fat, low-cholesterol diet is recommended. The cornerstone of pharmacotherapy is the use of bile acid sequestrants, such as cholestyramine or colestipol, which bind to bile acids in the intestine, promoting the excretion of sterols. Ezetimibe, a cholesterol absorption inhibitor, can also be beneficial. In severe cases, surgical intervention like ileal bypass may be considered. Early diagnosis and consistent management are essential to prevent or mitigate the serious complications associated with sitosterolemia.