Sitosterolemia is a rare, autosomal recessive inherited
sterol storage disease associated with high tissue and serum
plant sterol concentrations, caused by mutations in the
adenosine triphosphate-bind-ing cassette (
ABC) transporter ABCG5 or ABCG8 genes. Markedly increased serum concentration of
plant sterols. such as
sitosterol and
campesterol, cause premature
atherosclerosis and massive
xanthomas. Hitherto known treatments for
sitosterolemia, including a low-
sterol diet,
bile-salt binding resins, ileal bypass surgery and
low density lipoprotein (
LDL)
apheresis have not yielded sufficient reduction of serum
plant sterol levels and many patients show a sustained elevation of
plant sterol levels, subsequently developing premature atherosclerotic
cardiovascular diseases.
Ezetimibe, an inhibitor of intestinal
cholesterol absorption through its binding to Niemann-Pick C1-like 1 (NPC1L1), has been widely used for decreasing serum
LDL-cholesterol levels in patients with
hypercholesterolemia.
Ezetimibe also reduces the gastrointestinal absorption of
plant sterols, thereby also lowering the serum concentrations of
plant sterols. This pharmacological property of
ezetimibe shows its potential as a novel effective
therapy for
sitosterolemia. In the current review, we discuss the current
therapy for patients with
sitosterolemia and present two Japanese adolescent patients with this disease, one of whom underwent
percutaneous coronary intervention for accelerated
coronary atherosclerosis.
Ezetimibe administration in addition to conventional
drug therapy successfully reduced serum
sitosterol levels by 51.3% and 48.9%, respectively, in the two patients, demonstrating
ezetimibe as a novel and potent treatment agent for
sitosterolemia that could work additively with conventional
drug therapy.