Sitosterolemia is a rare inherited condition in which plant sterols accumulate in the blood and tissues. Plant sterols, including sitosterol, stigmasterol, and campesterol, are fatty substances found in vegetable oils and nuts. Individuals with sitosterolemia have extremely high levels of sitosterol (30 to 100 times higher than normal), along with mildly to moderately elevated levels of cholesterol in their blood. These plant sterols and cholesterol build up in the arteries, leading to premature thickening of the artery walls and early heart disease. Affected individuals may also develop small yellowish growths called xanthomas on or under the skin and in the tendons. Sitosterolemia is caused by mutations in the ABCG5 or ABCG8 gene. The condition is inherited in an autosomal recessive pattern. Treatment involves restricting foods that are high in plant and shellfish sterols, and taking medications that decrease the concentration of these products in the blood.

ABCG5 and ABCG8 genes can be helpful in detecting mutations and confirming the diagnosis.

GeneReviews offers additional details about management.