Sitosterolemia

What are the signs and symptoms of sitosterolemia?

There are typically very few symptoms. One symptom is when lipids build up and cause xanthomas, which are small, yellowish growths that can appear on the skin of hands, elbows, knees, buttocks, and heels. They can also grow on tendons; the Achilles tendon is a common spot. Large xanthomas can be painful and make it hard to move.

What causes sitosterolemia?

Sitosterolemia is a recessive genetic condition, meaning a child needs two copies of the abnormal gene to show the disease. (A child’s parent is very likely not affected.) It is caused by mutations in either the ABCG5 or ABCG8 gene. The disease causes the body to store plant sterols absorbed from a person’s diet in the blood and arteries, instead of excreting them in the gut.

How is sitosterolemia diagnosed?

Sitosterolemia isn’t always easy to diagnose. That’s because its symptoms mirror those found in conditions caused by other genetic disorders of high cholesterol levels, and cholesterol screening doesn’t generally detect the plant sterols that build up in sitosterolemia.

Genetic testing for the mutations that cause sitosterolemia usually confirms its presence. Measuring sitosterol levels can also diagnose the disease.

How we care for sitosterolemia

If your child has sitosterolemia, most of their treatment will happen at home. Treatment involves three elements: changes to diet, exercise, and medications.

• Diet: It can vary for each patient, but your child may be asked to eliminate plant oils — such as canola, corn, soybean, sunflower, olive, and palm — from meals. Avoiding chocolate, peanuts, almonds, and avocados, as well as shellfish, shrimp, and scallops, can also be helpful. We view a diet for sitosterolemia as an opportunity for your child to gain an appreciation for foods they might not otherwise eat. So we’ll work with your family to create a diet of mostly vegetables and fruits, as well as lean proteins such as chicken, tofu, and other foods that won’t increase sitosterol or other lipid levels.
• Medication: There are several types of medications that can help lower sterol levels. Your child’s medication treatment will be specific to their case and testing results. Typical medications work by blocking the absorption of cholesterol or by binding extra cholesterol in the intestines.
• Exercise:  Most days, about an hour for children and about 150 minutes for adults.

The Preventive Cardiology Clinic at Boston Children’s believes treatment of sitosterolemia is a partnership between you and your child and our doctors, nurse practitioners, nurses, and dieticians. We will always be available to discuss their medications, diet, and exercise, and any concern or development that arises — and we will work with you to modify your child’s diet and medication as they mature. Your child will also see us regularly for follow-up testing, and to discuss how you and they are managing the disease.

Treatment is a lifelong, day-to-day routine. You will not be alone in the care of your child.