NIH

Zebra of the Week: Sitosterolemia

January 26, 2026

Sitosterolemia is a rare inherited disorder characterized by abnormal accumulation of plant sterols in the blood and tissues. Plant sterols—including sitosterol, stigmasterol, and campesterol—are lipid compounds commonly found in vegetable oils and nuts. Individuals with sitosterolemia demonstrate markedly elevated plasma levels of sitosterol, typically 30 to 100 times higher than normal, accompanied by mildly to moderately increased cholesterol levels.

The accumulation of plant sterols and cholesterol within the arterial walls contributes to premature arterial thickening and the early onset of cardiovascular disease. Clinically, affected individuals may develop xanthomas, which present as small yellowish deposits on or beneath the skin and within tendons.

Sitosterolemia is caused by pathogenic variants in the ABCG5 or ABCG8 genes and is inherited in an autosomal recessive pattern.

Source:

(Accessed 2026, January 23). NIH. Sitosterolemia. https://rarediseases.info.nih.gov/diseases/7653/sitosterolemia