Itziar Lamiquiz-Moneo1, Lucía Baila-Rueda2, Ana M Bea2, Rocío Mateo-Gallego2, Sofía Pérez-Calahorra2, Victoria Marco-Benedí2, Antonio Martín-Navarro2, Emilio Ros3, Montserrat Cofán3, José Carlos Rodríguez-Rey4, Miguel Pocovi5, Ana Cenarro2, Fernando Civeira2. 1. Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Universidad de Zaragoza, Zaragoza, Spain. Electronic address: itziarlamiquiz@gmail.com. 2. Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), CIBERCV, Universidad de Zaragoza, Zaragoza, Spain. 3. Unitat de Lipids, Servei d'Endocrinologia i Nutrició, Institut d'Investigacions Biomediques August Pi i Sunyer, Hospital Clinic and CIBER Fisiopatologia de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Barcelona, Spain. 4. Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Instituto de Investigación Valdecilla (IDIVAL), Santander, Cantabria, Spain. 5. Departamento de Bioquímica, Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain.
Abstract
CONTEXT: Approximately 20% to 40% of clinically defined familial hypercholesterolemia (FH) cases do not show a causative mutation in candidate genes (mutation-negative FH), and some of them may have a polygenic origin. OBJECTIVE: The aim of this work was to study the prevalence of ABCG5/G8 genetic variants in mutation-negative FH, as defects in these genes relate to intestinal hyperabsorption of cholesterol and thus ABCG5/G8 variants could explain in part the mechanism of hypercholesterolemia. DESIGN, SETTING, AND PATIENTS: We sequenced the ABCG5/G8 genes in 214 mutation-negative FH and 97 controls. Surrogate markers of cholesterol absorption (5α-cholestanol, β-sitosterol, campesterol, stigmasterol, and sitostanol) were quantified by high-performance liquid chromatography-tandem mass spectrometry in both studied groups. RESULTS: We found 8 mutation-negative FH patients (3.73%) with a pathogenic mutation in ABCG5/G8 genes. We observed significantly higher concentration of surrogate markers of cholesterol absorption in mutation-negative FH than in controls. In addition, we found significantly higher concentrations of cholesterol absorption markers in mutation-negative FH with ABCG5/G8 defects than in mutation-negative, ABCG5/G8-negative FH. A gene score reflecting the number of common single nucleotide variants associated with hypercholesterolemia was significantly higher in cases than in controls (P = .032). Subjects with a gene score above the mean had significantly higher 5α-cholestanol and stigmasterol than those with a lower gene score. CONCLUSIONS: Mutation-negative FH subjects accumulate an excess of rare and common gene variations in ABCG5/G8 genes. This variation is associated with increased intestinal absorption of cholesterol, as determined by surrogate makers, suggesting that these loci contribute to hypercholesterolemia by enhancing intestinal cholesterol absorption.
CONTEXT: Approximately 20% to 40% of clinically defined familial hypercholesterolemia (FH) cases do not show a causative mutation in candidate genes (mutation-negative FH), and some of them may have a polygenic origin. OBJECTIVE: The aim of this work was to study the prevalence of ABCG5/G8 genetic variants in mutation-negative FH, as defects in these genes relate to intestinal hyperabsorption of cholesterol and thus ABCG5/G8 variants could explain in part the mechanism of hypercholesterolemia. DESIGN, SETTING, AND PATIENTS: We sequenced the ABCG5/G8 genes in 214 mutation-negative FH and 97 controls. Surrogate markers of cholesterol absorption (5α-cholestanol, β-sitosterol, campesterol, stigmasterol, and sitostanol) were quantified by high-performance liquid chromatography-tandem mass spectrometry in both studied groups. RESULTS: We found 8 mutation-negative FH patients (3.73%) with a pathogenic mutation in ABCG5/G8 genes. We observed significantly higher concentration of surrogate markers of cholesterol absorption in mutation-negative FH than in controls. In addition, we found significantly higher concentrations of cholesterol absorption markers in mutation-negative FH with ABCG5/G8 defects than in mutation-negative, ABCG5/G8-negative FH. A gene score reflecting the number of common single nucleotide variants associated with hypercholesterolemia was significantly higher in cases than in controls (P = .032). Subjects with a gene score above the mean had significantly higher 5α-cholestanol and stigmasterol than those with a lower gene score. CONCLUSIONS: Mutation-negative FH subjects accumulate an excess of rare and common gene variations in ABCG5/G8 genes. This variation is associated with increased intestinal absorption of cholesterol, as determined by surrogate makers, suggesting that these loci contribute to hypercholesterolemia by enhancing intestinal cholesterol absorption.
Authors: Noor Shafina Mohd Nor; Alyaa Mahmood Al-Khateeb; Yung-An Chua; Noor Alicezah Mohd Kasim; Hapizah Mohd Nawawi Journal: BMC Pediatr Date: 2019-04-11 Impact factor: 2.125