Sitosterolemia is a condition in which fatty substances (lipids) from vegetable oils, nuts, and other plant-based foods accumulate in the blood and tissues. These lipids are called plant sterols (or phytosterols). Sitosterol is one of several plant sterols that accumulate in this disorder, with a blood level 30 to 100 times greater than normal. Cholesterol, a similar fatty substance found in animal products, is mildly to moderately elevated in many people with sitosterolemia. Cholesterol levels are particularly high in some affected children. However, some people with sitosterolemia have normal cholesterol levels.

Sitosterolemia is caused by mutations in the ABCG5 or ABCG8 gene. These genes provide instructions for making the two halves of a protein called sterolin. This protein is involved in eliminating plant sterols, which cannot be used by human cells.

Only 80 to 100 individuals with sitosterolemia have been described in the medical literature. However, researchers believe that this condition is likely underdiagnosed because mild cases often do not come to medical attention. Studies suggest that the prevalence may be at least 1 in 50,000 people.

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Published Date: November 01, 2016
Published By: National Institutes of Health