Compound heterozygous mutations in ABCG5 or ABCG8 causing Chinese familial Sitosterolemia

BACKGROUND: Sitosterolemia (STSL), also known as phytosterolemia, is a rare autosomal recessive hereditary disease caused by mutations in the ABCG5 or ABCG8 genes. The disease is a result of disorders in lipoprotein metabolism, and is characterized by tendinous and tuberous xanthomas, elevated plasma cholesterol and phytosterol levels, and thrombocytopenia and hemolytic anemia in several patients. The manifestations of STSL are diverse and can easily be misdiagnosed. In recent years, cases of this disease in children have been reported in succession. There is therefore a need for clinicians to improve identification of STSL and perform early intervention. METHODS: We evaluated four children with STSL caused by genetic mutations in ABCG5 or ABCG8, as well as their family members, by analyzing their clinical characteristics and performing Trio-whole exome sequencing. The biological consequences of the mutations were analyzed using various bioinformatics software. We also analyzed the consequences of a mutation commonly observed in STSL patients on the structure of the protein involved. RESULTS: We identified five previously unreported pathogenic mutations of different phenotypes of STSL: ABCG5 NM_022436:c.1337G>A; ABCG8 NM_022437:c.965-1G>A, c.323-1G>C, c.1418C>G and c.1534G>A. We also report the structural changes brought about by a mutation common in STSL patients, as well as the possible consequences of these changes. CONCLUSIONS: Our findings further broaden the genotypic and phenotypic profiles of the onset of STSL in the pediatric population and provide information for the diagnosis and treatment of this disease.