Clinical features and genetic analysis of childhood Sitosterolemia : Two case reports and literature review

Abstract

Rationale: Sitosterolemia is a rare autosomal recessive disorder of dyslipidemia due to mutations of genes ABCG5 and ABCG8, leading to highly elevated plasma levels of plant sterols and expanded body pools of cholesterol. Patient concerns: We present a 9-year-old and a 7-year-old Chinese boy with hypercholesterolemia and xanthomas of sitosterolemia due to ABCG5 gene mutations. We also make a literature review of another 30 sitosterolemic children cases that have been reported with virulence ABCG5 gene mutations. Diagnosis: We took peripheral blood samples from 2 patients and their parents to conduct genetic analysis by next-generation sequencing (NGS) technologies. Interventions: The 2 patients received dietary modifications without pharmaceuticals treatment. Outcomes: A c.1166G>A (Arg389His) homozygosis mutation in exon 9 was observed in case 1, whereas a c.751C>T (Gln251*) homozygosis mutation in exon 6 was found in case 2. Literature review found another 30 pediatric cases with sitosterolemia due to ABCG5 gene mutation. The lipid profile was normalized and xanthomas got smaller with combined therapy of a combined lowcholesterol and low-phytosterols diet. Lessons: These suggested that in patients (especially Asian patients) with multiple xanthomas, severe hypercholesterolemia, or elevated low-density lipoprotein-cholesterol, sitosterolemia should be considered in the differential diagnosis. Early diagnosis is important, and restriction of both cholesterol and phytosterols diet should suggested for these patients. Abbreviations: ABC = adenosine triphosphate-binding cassette, ABCA1 = ATP-binding cassette subfamily A member 1, ABCG5 = ATP-binding cassette subfamily G member 5, ABCG8 = ATP-binding cassette subfamily G member 8, APOA1 = apolipoprotein A1, APOA5 = apolipoprotein A5, ApoB = apolipoprotein B, APOE = apolipoprotein E, FH = familial hypercholesterolemia, GC-MS = gas chromatography-mass spectrometry, HAMP = hepcidin antimicrobial peptide, HDL-C = high-density lipoprotein-cholesterol, HFE = homeostatic iron regulator, LCAT = lecithin-cholesterol acyltransferase, LDL-C = lowdensity lipoprotein-cholesterol, LDLR =low-density lipoprotein receptor, LDLRAP1 = low-density lipoprotein receptor adaptor protein 1, LIPA = lipase A, LIPC = lipase C, hepatic type, LIPI= lipase I, LPL = lipoprotein lipase, NGS = next-generation sequencing, PCSK9 = proprotein-convertase subtilisin/kexin type 9, SLC40A1 = solute carrier family 40 member 1, TC = total cholesterol, TFR2 = transferrin receptor 2, USF1 = upstream transcription factor 1.