Abstract: Objective: To analyze the clinical manifestations, laboratory tests, genetic diagnosis and serum phytosterol profile results of three children with sitosterolemia, in order to improve the diagnosis and therapy level of sitosterolemia. Methods: Retrospective analysis was made on the clinical characteristics and routine biochemical test results of 3 children diagnosed as sitosterolemia, who were firstly diagnosed in the dermatology of Wuxi Children's Hospital from April 2021 to April 2023. Full exon sequencing, sanger sequencing and plant sterol spectrum were performed. Following up for over a year to observe changes in clinical symptoms and laboratory test indicators in the affected children. Results: The skin xanthoma was the first symptom in 2 patients. Four different mutation types were detected and one new mutation sites was firstly found. Compound heterozygous mutation in the exon of ABCG8 were discovered in case 1 and 2 (ABCG8 NM_0224 37: c.1724G>A, p.G575D,  ABCG8 NM_0224 37: c.788G>A, p.R263Q). While compound heterozygous mutation in the exon of ABCG5 was discovered in patient 3 (ABCG5 NM_022436.2：c.751C>T, p.Gln251*, ABCG5 NM_022436.2: c.-76C>T). The levels of serum phytosterol profile in patient 1 and 2 before treatment were significantly higher than normal. All the 3 children were given a low sterol diet, and case 1 was combined with ezetimide. Following up for more than 1 year, the blood lipid levels of all three returned to normal. Serum phytosterol profile levels significantly decreased compared to those of prior treatment and skin xanthoma subsided in case 1 and case 2. Conclusion: Children with sitosterolemia usually present skin xanthomas near the joints, with elevated total cholesterol. Diagnosis requires genetic testing and serum plant sterol profiling results. Low phytosterol diet and ezetimibe are crucial for treatment of sitosterolemia.

Key words: skin xanthoma, sitosterolemia, gene detection, serum phytosterol profile