Browsing by Author "Bourbon, M."
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- Advantages and versatility of fluorescence-based methodology to characterize the functionality of LDLR and class mutation assignmentPublication . Benito-Vicente, A.; Etxebarria, A.; Alves, A.C.; Bourbon, M.; Martin, C.INTRODUCTION: Familial hypercholesterolemia (FH) is a common autosomal dominant disease with a frequency of 1:500 individuals in its heterozygous form. The genetic basis of FH is mostly mutations within the LDLR gene. Assessing the pathogenicity of LDLR variants is particularly important to give a patient a definitive diagnosis of FH. Current studies of LDLR activity ex vivo are based on the analysis of 125I-labeled lipoproteins or fluorescent-labeled LDL. The main purpose of this study was to compare the effectiveness of these two methods to assess LDLR functionality in order to validate a functional assay to analyse LDLR mutations.
- Advantages and Versatility of Fluorescence-Based Methodology to Characterize the Functionality of LDLR and Class Mutation AssignmentPublication . Etxebarria, A.; Benito-Vicente, A.; Alves, A.C.; Ostolaza, H.; Bourbon, M.; Martin, C.Familial hypercholesterolemia (FH) is a common autosomal codominant disease with a frequency of 1∶500 individuals in its heterozygous form. The genetic basis of FH is most commonly mutations within the LDLR gene. Assessing the pathogenicity of LDLR variants is particularly important to give a patient a definitive diagnosis of FH. Current studies of LDLR activity ex vivo are based on the analysis of 125I-labeled lipoproteins (reference method) or fluorescent-labelled LDL. The main purpose of this study was to compare the effectiveness of these two methods to assess LDLR functionality in order to validate a functional assay to analyse LDLR mutations. LDLR activity of different variants has been studied by flow cytometry using FITC-labelled LDL and compared with studies performed previously with 125I-labeled lipoproteins. Flow cytometry results are in full agreement with the data obtained by the 125I methodology. Additionally confocal microscopy allowed the assignment of different class mutation to the variants assayed. Use of fluorescence yielded similar results than 125I-labeled lipoproteins concerning LDLR activity determination, and also allows class mutation classification. The use of FITC-labelled LDL is easier in handling and disposal, cheaper than radioactivity and can be routinely performed by any group doing LDLR functional validations.
- Analysis of Genetic Markers for Cardiovascular Disorders in a Portuguese population with Familial HypercholesterolaemiaPublication . Gomes, A.; Santos, T.; Costa, L.; Bourbon, M.Familial Hypercholesterolaemia is a genetic disorder characterized by an increase in TC and LDLC leading to premature atherosclerosis (ATH) and cardiovascular disorders (CVD) but not all FH patients develops premature CVD. Early identification of FH patients at an even increased risk of developing CVD is important. Genetic markers could improve risk stratification for this patients. Inflammation has been considered to be involved in the pathogenesis of CVD and genetic and oxidative stress markers may also contribute to ATH and CVD outcome.
- Analysis of Genetic Markers for Cardiovascular Disorders in a Portuguese Population with Familial HypercholesterolaemiaPublication . Gomes, A.; Santos, T.; Costa, L.; Bourbon, M.Familial Hypercholesterolaemia (FH) is a genetic disorder that leads to an increase in levels of total and low density lipoprotein cholesterol promoting atherosclerosis (ATH) and premature cardiovascular disease (CVD). ATH and CVD are multifactorial disorders depending on both genetic and environmental factors and inflammation has been considered to be involved in the pathogenesis of ATH and CVD, namely the activity of pro-inflammatory cytokines and acute phase proteins. Also, there are other risk factors contributing to the development and progression of ATH and CVD as genetic and oxidative stress markers.
- Analysis of Genetic Markers for Cardiovascular Disorders in a Portuguese population with Familial HypercholesterolaemiaPublication . Gomes, A.; Santos, T.; Bourbon, M.Familial Hypercholesterolaemia (FH) is a genetic disorder leading to an increase in levels of total and low density lipoprotein cholesterol promoting atherosclerosis (ATH) and premature cardiovascular disease (CVD). Inflammation has been considered to be involved in the pathogenesis of CVD, namely the activity of pro-inflammatory cytokines and acute phase proteins. Genetic and oxidative stress markers may contribute to ATH and CVD outcome. We intended to investigate the role of genetic, inflammatory and oxidative biomarkers in the clinical outcome of FH patients and study its putative correlation with CVD. We selected 41 FH patients with CVD, 91 without CVD and 49 healthy individuals. All individuals were characterized through the determination of the lipid profile (high density lipoprotein, LDL and total cholesterol (TC), triglycerides (TG), apolipoproteinA, apolipoproteinB, lipoprotein(a)), measurement of serum concentration of inflammatory markers (ceruloplasmin, haptoglobin and C reactive protein), pro-inflammatory cytokines (interleukin-6 (IL6) and tumor necrosis factor-alpha (TNFα)), homocysteine and markers of antioxidant / pro-oxidant status (nitric oxid (NO) and oxidized LDL). Genetic characterization was achieved by the study of polymorphisms in the genes encoding for LPL, APOAV, APOCIII, TNF-α, IL6, MTHFR and NOS. The results showed that the group of FH patients with CVD presented increased TC (p<0,001) and LDL cholesterol (p=0,001) and apoB (p<0,001) levels and decreased apoA1 (p=0,021) levels in relation to the FH group without CVD. In the FH group with CVD it was observed the highest oxLDL and the lowest NO concentrations. APOAV-1131C and APOCIII 3238G allele were associated with higher TG levels (p=0,013; p=0,042) in the FH group without CVD. MTHFR 677T allele was associated with high TC levels (p=0,006) in the FH group with CVD. Markers of lipid metabolism are evident between the groups analyzed however inflammatory and genetic markers need further studies to improve our knowledge of their role in CVD outcome.
- Analysis of publicly available LDLR, APOB, and PCSK9 variants associated with familial hypercholesterolemia: application of ACMG guidelines and implications for familial hypercholesterolemia diagnosisPublication . Chora, J.R.; Medeiros, A.M.; Alves, A.C.; Bourbon, M.PurposeFamilial hypercholesterolemia (FH) is an autosomal disorder of lipid metabolism presenting with increased cardiovascular risk. Although more than 1,700 variants have been associated with FH, the great majority have not been functionally proved to affect the low-density lipoprotein receptor cycle. We aimed to classify all described variants associated with FH and to establish the proportion of variants that lack evidence to support their pathogenicity.MethodsWe followed American College of Medical Genetics and Genomics (ACMG) guidelines for the classification, and collected information from a variety of databases and individual reports. A worldwide overview of publicly available FH variants was also performed.ResultsA total of 2,104 unique variants were identified as being associated with FH, but only 166 variants have been proven by complete in vitro functional studies to be causative of disease. Additionally, applying the ACMG guidelines, 1,097 variants were considered pathogenic or likely pathogenic. Only seven variants were found in all five continents.ConclusionThe lack of functional evidence for about 85% of all variants found in FH patients can compromise FH diagnosis and patient prognosis. ACMG classification improves variant interpretation, but functional studies are necessary to understand the effect of about 40% of all variants reported. Nevertheless, ACMG guidelines need to be adapted to FH for a better diagnosis.
- Analysis of publicly available LDLR, APOB, and PCSK9 variants associated with familial hypercholesterolemia: application of ACMG guidelines and implications for familial hypercholesterolemia diagnosisPublication . Chora, J.R.; Medeiros, A.M.; Alves, A.C.; Bourbon, M.Familial Hypercholesterolemia (FH): Lipid metabolism autosomal dominant condition; Patients present elevated low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) values since birth - elevated cardiovascular risk.
- ApoB/ApoA1 ratio improves clinical criteria sensitivity for the identification of FH childrenPublication . Medeiros, A.M.; Alves, A.C.; Aguiar, P.; Bourbon, M.
- APOB: old gene, new perspective for Familial HypercholesterolaemiaPublication . Alves, A.C.; Etxebarria, A.; Martin, C.; Bourbon, M.Familial hypercholesterolemia (FH) is one of the most common diseases of lipid metabolism, has an autosomal dominant inheritance and was the first genetic disorder of lipid metabolism to be characterized molecularly. FH usually results from inherited defects in the low density lipoprotein receptor (LDLR) gene and is characterised by increased circulating low density lipoprotein (LDL) cholesterol that leads to lipid accumulation in arteries and tendons (xanthomas), causing premature arteriosclerosis and coronary heart disease. Mutations in other genes as the apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin type 9 gene (PCSK9) are rare causes of FH. Until now only a few mutations in exon 26 and 29 have been reported to cause FH, being the APOB3527 the most common. The main aim of this project was to identify and characterize the genetic cause of severe hypercholesterolaemia in individuals with clinical diagnosis of FH, without mutations in LDLR and PCSK9 or in fragments of exon 26 and 29 of APOB routinely screened.
- Applicability of the low-density lipoprotein cholesterol gene score in a south European populationPublication . Mariano, C.; Futema, M.; Humphries, S.E.; Bourbon, M.Aim: The correct identification of the dyslipidaemia is of great importance in order to implement specific interventions, especially for cardiovascular disease (CVD) prevention. The Global Lipids Genetics Consortium (GLGC) reported 158 loci associated with lipid traits, by genome-wide association studies (GWAS), although practical value of GWAS approach is still a subject of debate, half of these loci are previously known to influence serum lipid concentrations. Previous studies (Talmud et al., 2013; Futema et al., 2015) have demonstrated that the co-inheritance of low-density lipoprotein (LDLC)-raising alleles from 6 of these SNPs is associated with the Familial Hypercholesterolaemia (FH) phenotype. Here we investigated the applicability of the LDL-C genetic risk score in the Portuguese FH population.