Emulsões artificiais sem proteína simulando quilomicrons e remanescentes de quilomícron foram preparadas por sonicalcação de trioleína, lecitina, colesteril oleato e colesterol em solução aquosa. A seguir foram ultracentrifugadas em gradiente descontínuo de densidade. As emulsões, marcadas com 3H-trioleína e 14C-colesteril oleato foram injetadas via intra-arterial em ratos controle e em ratos tratados com Triton WR1339, sulfato de protamina e heparina, medindo-se a seguir a remoção plasmática do colesteril-ester e dos triglicérides, durante dez minutos. O Triton WR 1339 e a protamina inibiram a lipólise dos quilomícrons artificiais, diminuindo a remoção destas partículas do plasma. O Triton WR 1339 mostrou ser mais efetivo que a protamina nestes efeitos. Por outro lado, a heparina promoveu uma lipólise rápida e brusca nos quilomícrons artificiais, assim como uma aceleração na remoção destas partículas do plasma. Em contraste flagrante com esses resultados, o metabolismo dos remanescentes de quilomícron não foi consideravelmente afetado pelo tratamento com Triton e heparina. Estas experiências indicam que as emulsões artificiais reproduzem o comportamento metabólico dos quilomícrons e remanescentes de quilomícron naturais, em condições em que a atividade da lipase lipoproteica esteja alterada. / Protein-free emulsions models of chylomicrons and chylomicron remnants were prepared by sonicating triolein, lecithin., cholesteryl oleate and cholesterol in aqueous saline media, followed by ultracentrifugation in density gradient solution. The 3H-triolein and 14C-cholesteryl oleate labeled emulsions were injected into the carotid artery of control rats and rats treated with Triton WR 1339, protamine sulphate and heparin. Plasma removal of both labels was measured during ten minutes in two minutes intervals. Triton WR 1339 and protamine sulphate strongly inhibited lipolysis of chylomicron-like emulsions leading to delayed removal of the particles from blood. Triton WR 1339 de appeared to be more effective than protamine to elicit these effects. On the other hand, heparin produced instantaneous lipolysis of the chylomicron-like particles markedly enhancing its removal from plasma. Contrarily, chylomicron remnant-like emulsions were not considerably affected either by Triton WR 1339 or by heparin treatment. The above described results obtained with artificial emulsions support current concepts on the metabolic behavior of natural chylomicron and remnant submitted to changes in lipoprotein lipase action.

Lipoprotein lipase (LPL) is a key enzyme in lipoprotein metabolism. The enzyme catalyzes hydrolysis of triacylglycerols (TG) of chylomicrons and of very low density lipoproteins (VLDL). However, the mechanisms involved in the regulation of this protein are not fully understood yet. Therefore, the aim of the theses is to study selected aspects of LPL activity regulation. Recently discovered apolipoprotein A-V (apo A-V) substantially affects triglyceridemia and it is presumed that it may function as LPL activator. However, its concentration in the blood is extremely low and we therefore investigated whether most of apo A-V could be bound to the heparan sulfate proteoglycan (HSPG) of vascular wall similarly to LPL. Intravenous heparin application in healthy volunteers resulted in an expected increase in LPL activity but apo A-V concentration did not change. Our results do not support the hypothesis that most of apo A-V is bound to HSPG of the capillary endothelium. An alcohol consumption plays also a role in LPL regulation - the long-term moderate alcohol consumption is known to increase enzyme activity; on the contrary, it is presumed that LPL activity is inhibited immediately after alcohol consumption. However, the direct evidence for such a premise is missing. The other aim of the theses was to...

Indiana University-Purdue University Indianapolis (IUPUI) / The incidence of Metabolic Syndrome (MetS) is increasing worldwide and accompanied by elevated risks for cardiovascular disease (CVD) and other subsequent comorbidities. MetS is associated with increased circulating triglycerides. A key enzyme involved in triglyceride (TG) clearance is lipoprotein lipase (LPL) whose activity is modulated by a variety of factors. Recent literature has identified the importance of angiopoietin-like proteins (ANGPTL) as regulators of LPL activity and has hypothesized a model in which three of these proteins interact with LPL to regulate the partitioning of TG metabolism from adipose to skeletal muscle. The work detailed in this dissertation adds to the model of ANGPTL regulation of LPL by establishing how ANGPTL8 modulates the ability of ANGPTL3 and ANGPTL4 to inhibit LPL activity in the bloodstream and localized environments, respectively. In the updated model, elevated insulin concentrations result in increased hepatic ANGPTL3/8 secretion and increased ANGPTL4/8 in adipose tissue. ANGPTL3/8 works as an endocrine molecule to inhibit skeletal muscle LPL from hydrolyzing circulating TG. Simultaneously, ANGPTL4/8 works in a paracrine mechanism to bind LPL on the endothelial vasculature adjacent to adipose tissue to alleviate ANGPTL4-mediated LPL inhibition and also prevent ANGPTL3/8 inhibition of localized LPL. Thus, in the postprandial state free fatty acids (FFA) from the hydrolysis of TG are directed into adipocytes for storage. Under fasting conditions, ANGPTL8 production is decreased in adipocytes and hepatocytes. This decreased production results in diminished ANGPTL4/8 and ANGPTL3/8 secretion from their respective tissues. As a result, ANGPTL4 inhibits adipocyte localized LPL activity while ANGPTL3 at physiological concentrations has minimal effect on LPL activity. Furthermore, any ANGPTL3/8 which is produced has its LPL-inhibitory ability diminished by the circulating apolipoprotein ApoA5. LPL is more active in skeletal muscle compared to adipose tissue where energy is shunted towards utilization in the muscle and away from storage in adipose tissue. A complete understanding of LPL regulation by ANGPTL proteins can potentially provide therapeutics targets for MetS.

L’hyperchylomicronémie familiale est un trait monogénique caractérisé par un taux de triglycérides plasmatiques à jeun supérieur à 10 mmol/L (la normale étant de 1,7 mmol/L). L’hyperchylomicronémie familiale est le plus souvent causée par une déficience dans le gène LPL (pour lipoprotéine lipase). La déficience en lipoprotéine lipase (LPLD) est aussi associée à un risque élevé de pancréatite. La pancréatite en soi est reconnue comme un trait complexe génétique dont plusieurs gènes sont associés à sa susceptibilité. Étant donné l’expression variable de la pancréatite chez les patients LPLD, les résultats de ce mémoire présentent certains facteurs génétiques pouvant être responsables du risque de l’expression de la pancréatite aigüe récurrente chez les sujets LPLD. L’analyse par séquençage des régions codantes et promotrices des gènes CTRC (pour « Chymotrypsin C ») et SPINK1 (pour « Serine protease inhibitor Kazal type 1 ») a été effectuée chez 38 patients LPLD et 100 témoins. Ces deux gènes codent pour des protéines impliquées dans le métabolisme des protéases au niveau du pancréas et ont déjà été associés avec la pancréatite dans la littérature. Notre étude a permis d’identifier une combinaison de deux polymorphismes (CTRC-rs545634 et SPINK1-rs11319) associée significativement avec la récidive d’hospitalisations pour douleur abdominale sévère ou pour pancréatite aigüe récurrente chez les patients LPLD (p<0,001). Ces résultats suggèrent que le risque de récidive de pancréatite chez les patients LPLD peut être influencé par des variants dans des gènes de susceptibilité à la pancréatite. L’identification de biomarqueurs génétiques améliore la compréhension des mécanismes physiopathologiques de la pancréatite chez les patients LPLD ce qui, par conséquent, permet de mieux évaluer et caractériser les risques de pancréatite afin d'adapter un plan d'intervention préventif pour ces patients. / Familial hyperchylomicronemia is a monogenic trait characterized by an increased fasting plasma triglyceride levels ≥ 10 mmol/L (normal is 1.7 mmol/L). Familial hyperchylomicronemia is most often caused by a deficiency in the LPL gene. Lipoprotein lipase deficiency (LPLD) is also associated with an increased risk of pancreatitis. Pancreatitis is recognized as a complex genetic trait and several genes are associated with its susceptibility. Considering the variable expression of pancreatitis in LPLD patients, results of this manuscript demonstrate that genetic factors may be responsible of the increased risk of recurrent acute pancreatitis episodes in LPLD subjects. The sequencing analysis of the coding and promoters regions of CTRC gene (for Chymotrypsin C) and SPINK1 gene (for Serine protease inhibitor Kazal type 1) was performed. These two genes encode proteins involved in the metabolism of the pancreas proteases and have been associated with pancreatitis in literature. A combination of two polymorphisms (CTRC-rs545634 and SPINK1-rs11319) have been identified and associated with recurrent hospitalizations for severe abdominal pain or recurrent acute pancreatitis in LPLD patients (p <0.001). These results suggest that the risk of recurrent episodes of pancreatitis in LPLD patients may be influenced by variants in susceptibility genes. The identification of genetic biomarkers improves the understanding of the pathophysiological mechanisms of pancreatitis in LPLD patients which therefore helps to assess and characterize the risk of pancreatitis to adapt preventive intervention plan for these patients.

La déficience partielle en lipoprotéine lipase (LPLD) est associée à une augmentation du risque cardiométabolique chez les hommes et les femmes. L’adiponectine, le syndrome métabolique et la ménopause sont des modulateurs importants de ce risque. L’objectif de cette étude était d’évaluer la contribution de l’adiponectine au profil de risque cardiométabolique de femmes porteuses de variants dans le gène LPL connus pour être associés avec la LPLD. L'échantillon étudié comprenait 568 femmes d'origine canadienne-française, dont 127 avec une LPLD et 441 non LPLD (contrôles). L'influence de l'adiponectine sur le risque associé à la LPLD a été évaluée en utilisant des analyses de régression multiples prenant en compte l’influence du statut ménopausique, des variables anthropométriques, du bilan lipidique, de la glycémie à jeun et du tabagisme. Les résultats montrent que les niveaux d'adiponectine étaient significativement plus faibles dans les groupes LPLD. La contribution des valeurs faibles d’adiponectine au profil de risque cardiométabolique des sujets LPLD était indépendante du statut ménopausique et de toutes les autres covariables étudiées. Cela suggère que l'adiponectine contribue au profil de risque cardiométabolique chez les femmes porteuses d’une mutation connue pour être associée avec la LPLD. / The cardiovascular risk significantly increases after menopause. Lipoprotein lipase (LPL) is a key enzyme in the metabolism of triglyceride (TG)-rich lipoproteins which contributes to cardiometabolic homeostasis. Adiponectin is an adipocytokine which also influences the cardiometabolic status. The objective of this study was to evaluate the contribution of plasma adiponectin to the cardiometabolic status of women carrying loss-of-function LPL gene variants (LPLD). A total of 568 French Canadian women (127 LPLD and 441 controls) were included. The association of plasma adiponectin with LPLD was assessed using multiple regression models. Cardiometabolic covariates included anthropometrics, lipids (TG, HDL-C, LDL-C, apo B), fasting glucose and smoking. Mean plasma adiponectin concentration was significantly lower in women with LPLD. Women carrying loss-of function LPL gene mutations also presented a significantly higher risk of coronary artery disease. In conclusion, these results suggest that low plasma adiponectin significantly contributes to the cardiometabolic risk profile of postmenopausal women carrying loss-of-function LPL gene mutations, independently of anthropometrics, lipids and other covariates.

La déficience partielle en lipoprotéine lipase (LPLD) est associée à une augmentation du risque cardiométabolique chez les hommes et les femmes. L’adiponectine, le syndrome métabolique et la ménopause sont des modulateurs importants de ce risque. L’objectif de cette étude était d’évaluer la contribution de l’adiponectine au profil de risque cardiométabolique de femmes porteuses de variants dans le gène LPL connus pour être associés avec la LPLD. L'échantillon étudié comprenait 568 femmes d'origine canadienne-française, dont 127 avec une LPLD et 441 non LPLD (contrôles). L'influence de l'adiponectine sur le risque associé à la LPLD a été évaluée en utilisant des analyses de régression multiples prenant en compte l’influence du statut ménopausique, des variables anthropométriques, du bilan lipidique, de la glycémie à jeun et du tabagisme. Les résultats montrent que les niveaux d'adiponectine étaient significativement plus faibles dans les groupes LPLD. La contribution des valeurs faibles d’adiponectine au profil de risque cardiométabolique des sujets LPLD était indépendante du statut ménopausique et de toutes les autres covariables étudiées. Cela suggère que l'adiponectine contribue au profil de risque cardiométabolique chez les femmes porteuses d’une mutation connue pour être associée avec la LPLD. / The cardiovascular risk significantly increases after menopause. Lipoprotein lipase (LPL) is a key enzyme in the metabolism of triglyceride (TG)-rich lipoproteins which contributes to cardiometabolic homeostasis. Adiponectin is an adipocytokine which also influences the cardiometabolic status. The objective of this study was to evaluate the contribution of plasma adiponectin to the cardiometabolic status of women carrying loss-of-function LPL gene variants (LPLD). A total of 568 French Canadian women (127 LPLD and 441 controls) were included. The association of plasma adiponectin with LPLD was assessed using multiple regression models. Cardiometabolic covariates included anthropometrics, lipids (TG, HDL-C, LDL-C, apo B), fasting glucose and smoking. Mean plasma adiponectin concentration was significantly lower in women with LPLD. Women carrying loss-of function LPL gene mutations also presented a significantly higher risk of coronary artery disease. In conclusion, these results suggest that low plasma adiponectin significantly contributes to the cardiometabolic risk profile of postmenopausal women carrying loss-of-function LPL gene mutations, independently of anthropometrics, lipids and other covariates.

It has been found in previous studies that there is a correlation between the placenta regulatory genes and the weight gain of the mother, Body Mass Index (BMI) as well as the birthweight of the fetus. When the mother gains weight / is overweight, this will affect the gene expression in the placenta, and in turn this triggers the weight gain of the fetus. The aim of the study was to investigate the correlation between the lipoprotein lipase gene and the mother's BMI, weight gain and the child's birth weight by extracting RNA from the placentas and analysing its quality and concentration. cDNA was generated from RNA using reverse transcription and gene expression was amplified using real-time PCR. The data from real-time PCR was used in the comparative Ct-method to calculate a 2˄(-ΔΔCt)-value which represents the RNA-level of the LPL-gene. Lastly this value was analysed by using the two-statistic methods, Pearson's rank correlation and Spearman's correlation, which showed that the value of the correlation coefficient for all the variables was close to the value of zero. The closer the value is to zero, the weaker the association becomes between the different variables. The correlation was 0.045, 0.112 and 0.044 for the child's birth weight, mother's BMI respective weight gain. The results from this study shows that there is no correlation between LPL and the mother's weight gain, BMI, or the child's birth weight.

L’hypertriglycéridémie (hyperTG) est une dyslipidémie fréquente, caractérisée par une augmentation de la concentration plasmatique en triglycérides (TG). L’hyperTG est considérée comme un facteur de risque indépendant de la maladie cardiovasculaire, particulièrement de la maladie coronarienne athérosclérotique. Plusieurs facteurs environnementaux et génétiques ont été associés avec l’hyperTG. Cependant, près de 90% des cas d’hyperTG primaire sont encore incomplètement caractérisés au niveau moléculaire. Dernièrement, la protéine GPIHBP1 (glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1), qui a un rôle clef dans le métabolisme des TG, a été associée à l’expression d’hyperTG sévère et rare chez l’humain. Ce mémoire présente les résultats de nos travaux qui ont été effectués afin d’identifier de nouvelles bases moléculaires associées à l’expression de l’hyperTG dans le locus du gène GPIHBP1. Nous avons observé que le polymorphisme GPIHBP1 g.-469G>A (rs72691625), dont la fréquence de l’allèle mineure a été évaluée à 19,6% dans notre échantillon, serait associé à l’expression d’hyperTG (TG ≥ 2mmol/L) dans une population canadienne-française. Ce polymorphisme est associé à un risque 1,67 fois plus grand d’exprimer une triglycéridémie ≥ 2mmol/L chez les porteurs hétérozygotes et 5,7 fois plus grand chez les porteurs homozygotes, comparativement aux non-porteurs. Ce risque d’hyperTG serait exacerbé par la présence concomitante d’une mutation hypertriglycéridémiante dans le gène codant pour la lipoprotéine lipase. La présence de ce polymorphisme serait particulièrement associée à l’expression de la dysbêtalipoprotéinémie familiale et de l’hypertriglycéridémie familiale endogène. GPIHBP1 g.-469G>A est le premier polymorphisme fréquent identifié dans le promoteur du gène à être associé avec l’expression d’hyperTG. GPIHBP1 émerge de plus en plus comme un gène candidat intéressant pour la recherche de nouvelles bases moléculaires pouvant expliquer certaines formes d’hyperTG primaire fréquente. / Hypertriglyceridemia (hyperTG) is a frequent dyslipidemia referring to an increased fasting plasma triglyceride (TG) level ≥ 2 mmol/L. HyperTG is an independent risk factor for cardiovascular disease, such as coronary artery diseases. Several environmental and genetic factors have been associated with hyperTG. Although several gene factors were associated with hyperTG, nearly 90% of cases of primary hyperTG are still incompletely characterized at the molecular level. Recently, few cases of rare and severe hyperTG have been associated with some rare polymorphisms in the gene coding for GPIHBP1 (glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1). This manuscript resumes our research regarding the identification of new molecular bases associated with the expression of frequent hyperTG subtypes in the gene locus GPIHBP1. Our results show that the GPIHBP1 g.-469G>A polymorphism (rs72691625), whose the minor allele frequency was estimated to 19.6% in our sample, was associated with the expression of hyperTG (TG ≥ 2 mmol/L) in a French-Canadian population. Subjects heterozygous and homozygous for this polymorphism respectively had a 1.67-fold and 5.70-fold increased risk to exhibit plasma TG levels ≥ 2mmol/L as compared to non-carriers. This increased risk of hyperTG observed in g.-469A carriers seems to be exacerbated by the concomitant presence of a frequent loss-of-function lipoprotein lipase gene variant. This polymorphism seems also particularly associated with dysbetalipoproteinemia and familial hypertriglyceridemia. The g.-469G>A polymorphism is the first common polymorphism in the GPIHBP1 gene promoter to be associated with the expression of hyperTG. GPIHBP1 emerges as a significant candidate for the molecular based of primary hyperTG.

Objetivo: O impacto da artrite idiopática juvenil (AIJ) nas doenças periodontais é controverso, provavelmente devido à heterogeneidade de sexo e idade. Assim sendo, avaliou-se uma população homogênea com AIJ em relação às doenças periodontais e dislipidemia. Métodos: Trinta e cinco pacientes púberes e pós-púberes com AIJ do sexo feminino e 35 controles saudáveis comparáveis em relação ao sexo e idade foram avaliadas de acordo com dados demográficos, avaliação periodontal e dental completa, lipoproteínas em jejum e anticorpos antilipoproteína lipase. Foram avaliados também os escores da AIJ, exames laboratoriais, raio-X panorâmico e tratamento. Resultados: A idade atual foi semelhante nas pacientes e controles (11,90 ± 2,0 vs. 12,50 ± 3,0 anos; p=0,289). As avaliações periodontais mostraram que índice gengival, índice de placa, índice de sangramento e índices clínicos de inserção dentária foram semelhantes em pacientes e controles (p > 0,05), com exceção do aumento gengival no primeiro grupo (p < 0,0001). Análise realizada entre os pacientes com e sem gengivite mostrou que o uso de ciclosporina foi mais frequentemente observado nas pacientes com gengivite (37% vs. 0%; p=0,01), enquanto não foram evidenciadas diferenças demográficas, escores da AIJ, marcadores inflamatórios e perfil lipídico em ambos os grupos. Destacam-se que parâmetros de avaliação periodontal foram correlacionados com os escores da AIJ [índice gengival (IG) e Escola Paulista de Medicina - Range of Motion (EPM-ROM) (rs=+0,392; p=0,024); índice gengival (IG) e Childhood Health Assessment Questionnaire (CHAQ) (rs=+0,402; p=0,020); e índice de placa (IP) e escala visual analógica (EVA) do médico (rs=+0,430; p=0,013)]. Além disso, a avaliação odontológica demonstrou que os escores de atividade da AIJ apresentaram correlação positiva com dentes cariados, perdidos e obturados (CPO-D) com: escore de atividade da doença (JADAS27) (rs=+0,364; p=0,037), EVA do médico (rs=+0,401; p=0,021) e EVA do paciente (rs=+0,364; p=0,037). Conclusão: Demonstrou-se que doenças periodontais e dentais são semelhantes em AIJ e controles, e que estas condições são influenciadas por parâmetros da doença / Objective: The impact of juvenile idiopathic arthritis (JIA) in periodontal diseases is controversial probably due to sex and age heterogeneity. We therefore evaluated a homogeneous JIA population about periodontal diseases and dyslipidemia. Methods: Thirty-five female pubertal and post-pubertal JIA patients and thirty-five sex/age comparable healthy controls were evaluated according to demographic data, complete periodontal and dental evaluation, fasting lipoproteins, and anti-lipoprotein lipase antibodies. JIA scores, laboratorial tests, panoramic X-ray, and treatment were also assessed. Results: Current age was similar in JIA patients and controls (11.90 ± 2.0 vs. 12.50 ± 3.0 years, p=0.289). Complete periodontal assessments revealed that gingival index, dental plaque, gingival bleeding, and clinical dental attachment indices were alike in JIA patients and controls (p > 0.05), except for gingival enlargement in former group (p < 0.0001). Further analysis of patients with and without gingivitis revealed that cyclosporine use was more often observed in JIA patients with gingivitis (37% vs. 0%, p=0.01), whereas no differences were evidenced in demographic, JIA scores, inflammatory markers, and lipid profile in both groups. Of note, parameters of periodontal assessment were correlated with JIA scores [gingival index (GI) and \"Escola Paulista de Medicina\" - Range of Motion (EPM-ROM) (rs=+0.392, p=0.024); gingival index (GI) and Childhood Health Assessment Questionnaire (CHAQ) (rs=+0.402, p=0.020); and plaque index (PI) and physician visual analog scale (VAS) (rs=+0.430, p=0.013)]. In addition, evaluation of dental assessment demonstrated that JIA activity scores had positive correlation with decayed, missing, and filled teeth (DMF-T) and: juvenile arthritis disease activity score (JADAS-27) (rs=+0.364, p=0.037), physician VAS (rs=+0.401, p =0.021) and patient VAS (rs=+0.364, p=0.037). Conclusion: We demonstrated that periodontal and dental diseases were similar in JIA and controls, and we also showed that these conditions are influenced by disease parameters

L’hypertriglycéridémie (HTG) correspond à une accumulation des lipoprotéines riches en triglycérides (LRTG) dans la circulation plasmatique, conséquence d’une augmentation de leur synthèse ou plus classiquement décrit, d’une diminution de leur catabolisme. Dans près de 50% des cas, aucune cause génétique n’est identifiée chez les patients présentant une présentant une HTG sévère, aussi bien dans le cadre du syndrome de chylomicronémie familiale (FCS) que dans celui du syndrome de chylomicronémie multifactorielle (MCS). Pour améliorer nos connaissances et la caractérisation de ces patients, la conduction de corrélations phénotypes-génotypes précises grâce à une collaboration clinico-biologique étroite, ainsi que le développement d’outils de diagnostic moléculaire performants, demeurent un enjeu majeur. Premièrement, l’évaluation de la concentration pré-héparinique en LPL et l’activité post-héparinique 60 minutes après l’injection d’héparine chez 62 patients MCS caractérises génétiquement a permis la mise en évidence deux sous-groupes chez ces patients. Deuxièmement, le développement d’une stratégie séquençage de nouvelle génération permettant d’explorer simultanément les 9 gènes les plus prévalents dans les hypercholestérolémies, les hypocholestérolémies et les hypertriglycéridémies, a permis de détecter les variants nucléotidiques avec une sensibilité équivalente au séquençage Sanger mais aussi de détecter des grands réarrangements. L’ensemble des résultats souligne la complexité des mécanismes de régulation du métabolisme des LRTG et l’intérêt de l’étude des interactions gène-gène. Ainsi, ces travaux ont permis de mettre en évidence de nouvelles hypothèses à explorer pour la compréhension des mécanismes physiopathologiques des HTG sévères et d’améliorer les outils disponibles pour les études de corrélation génotype-phénotype / Hypertriglyceridemia (HTG) correspond to an increase of triglyceride-rich lipoproteins (TGRL) circulating concentration, as a consequence of an increase in the synthesis of or a decrease in their catabolism, most classically described. In nearly 50% of patients with severe hypertriglyceridemia (HTG), no genetic cause is identified, either in familial chylomicronemia syndrome (FCS) or in multifactorial chylomicronemia syndrome (MCS). To gain new insights and to improve patient’s characterization, it remains important to conduct accurate phenotype-genotype association studies through close collaboration with referent lipidologists, and to develop high-performance tools for molecular diagnosis. Firstly, the assessment of pre-heparin LPL concentration as well as LPL activity 60 minutes after heparin injection, enabled the identification of two subgroups within 62 genotyped MCS patients Secondly, the development of a new sequencing generation workflow exploring simultaneously the 9 most prevalent genes in dyslipidemia, allowed the detection of single nucleotide variations with sensitivity equivalent to Sanger sequencing, but also allowed the detection of copy number variations. Collective consideration of the results underlines the complexity of the regulation mechanisms of TGRL metabolism and the interest of gene-gene interactions study. Thus, the studies presented herein bring new hypothesis to explore for understanding the pathophysiological mechanisms of severe HTG and to improve molecular diagnosis tools available for phenotype-genotype association studies