Background: Homozygous familial hypercholesterolemia (HoFH), due to the LDLR gene defect, is very rare. Drugs are largely not effective enough for HoFH patients except LDL apheresis or liver transplantation combined with cholesterol-lowering drugs. However, pseudohomozygous familial hypercholesterolemia, also known as sitosterolemia, is a recessively inherited disorder that results from mutations in either ABCG5 or G8 proteins, with hyperabsorption of dietary sterols and decreased hepatic excretion of plant sterols and cholesterol. Ezetimibe appears to reduce plasma plant sterol concentrations in patients with sitosterolemia in previous studies. In this study, we compare the clinical manifestations and treatment outcome of these two diseases.
Methods: We conducted a retrospective review of 10 patients diagnosed with HoFH and five patients with pseudohomozygous familial hypercholesterolemia in our pediatric endocrinology department. HoFH and sitosterolemia were diagnosed by molecular study of these patients and their parents. Lipid profile before and after treatment was analyzed.
Results: Seven HoFH patients showed a reduction of more than 50% of the total cholesterol levels in response to conventional drug therapy (high-dose statin with ezetimibe). The low-density lipoprotein—cholesterol levels of three HoFH patients decreased to lower than 160 mg/dL. None of HoFH patient’s treatment results meet the current treatment target endpoint. Sitosterolemia patients were on ezetimibe therapy and had satisfactory total serum cholesterol levels, though their plant sterol levels were still higher than normal.
Conclusions: Pseudohomozygous familial hypercholesterolemia must be distinguished from homozygous familial hypercholesterolemia, as these two disease mandates different treatments and has a different prognosis. Despite aggressive therapy, HoFH patients are not well-controlled; atherosclerosis may progress. In contrast, total cholesterol levels can be well-controlled after ezetimibe treatment in sitosterolemia patients.
