Sitosterolemia with Double Variant in ABCG8 gene: A Case Report

Introduction Sitosterolemia is an autosomal recessive genetic disorder characterized by increased intestinal absorption of plant sterols. It is caused by pathogenic variants in the ABCG5 or ABCG8 genes, which encode subunits of transporters belonging to the ABC (ATP-Binding Cassette) protein family, responsible for the efflux of sterols from enterocytes and hepatocytes into the intestinal lumen. Clinically, it presents with elevated plasma plant sterol levels, dyslipidemia, cutaneous or tendon xanthomas, and premature atherosclerosis. Case Presentation We report the case of an 8-year-old boy with dizziness and photopsias since age 6, severe dyslipidemia without obesity or a family history of cardiovascular disease. The lipid profile showed persistently elevated total cholesterol and LDL. Molecular analysis revealed two compound heterozygous variants in the ABCG8 gene, confirming the diagnosis of sitosterolemia. Treatment with ezetimibe and a plant sterol-restricted diet was initiated, with a favorable biochemical response. Conclusions This case highlights the clinical relevance of sitosterolemia in pediatrics and underscores the value of genetic diagnosis as a key tool in precision medicine applied to hereditary dyslipidemias.