Search

Objective: Genetic determinants of severe hypertriglyceridemia include both common variants with small effects (assessed using polygenic risk scores) plus heterozygous and homozygous rare variants in canonical genes directly affecting triglyceride metabolism. Here, we broadened our scope to detect associations with rare loss-of-function variants in genes affecting noncanonical pathways, including those known to affect triglyceride metabolism indirectly. Approach and Results: From targeted next-generation sequencing of 69 metabolism-related genes in 265 patients of European descent with severe hypertriglyceridemia (≥10 mmol/L or ≥885 mg/dL) and 477 normolipidemic controls, we focused on the association of rare heterozygous loss-of-function variants in individual genes. We observed that compared with controls, severe hypertriglyceridemia patients were 20.2× (95% CI, 1.11–366.1; P =0.03) more likely than controls to carry a rare loss-of-function variant in CREB3L3 , which encodes a transcription factor that regulates several target genes with roles in triglyceride metabolism. Conclusions: Our findings indicate that rare variants in a noncanonical gene for triglyceride metabolism, namely CREB3L3 , contribute significantly to severe hypertriglyceridemia. Secondary genes and pathways should be considered when evaluating the genetic architecture of this complex trait.

Background We previously showed that levels of prebeta‐1 high‐density lipoprotein (HDL), the principal acceptor of cholesterol effluxed from cells, including artery wall macrophages, are positively associated with coronary heart disease (CHD) and myocardial infarction (MI) risk. Methods and Results In a multiethnic follow‐up cohort of 1249 individuals from University of California–San Francisco clinics, we determined the degree to which prebeta‐1 HDL levels, both absolute and percentage of apolipoprotein AI, are associated with CHD and history of MI. Independent, strong, positive associations were found. Meta‐analysis revealed for the absolute prebeta‐1 HDL for the top tertile versus the lowest, unadjusted odds ratios of 1.90 (95% CI, 1.40–2.58) for CHD and 1.79 (95% CI, 1.35–2.36) for MI. For CHD, adjusting for established risk factors, the top versus bottom tertiles, quintiles, and deciles yielded sizable odds ratios of 2.37 (95% CI, 1.74–3.25, P P P Conclusions Analysis of 2507 subjects showed conclusively that levels of prebeta‐1 HDL are strongly associated with a history of CHD or MI, independently of traditional risk factors. Addition of prebeta‐1 HDL can significantly improve clinical assessment of risk of CHD and MI.

Introduction: Inflammation plays an important role in the induction of CAD and the progression to deadly coronary syndromes. Cytokines are key mediators of inflammation, both in pro- and anti-inflammatory capacities. HDL has a vital role in the maintenance of cardiovascular health, and recent discoveries highlight the diversity of HDL functions to include the transport of lipid signaling molecules, microRNAs, and other effectors of metabolic regulation. Given the importance of HDL in transporting molecules involved in cardiovascular health, we questioned if HDL has a direct role in transporting cytokines and effecting inflammatory responses in CAD. Hypothesis: HDL plays an important role in the transport of cytokines involved in CAD. Methods: To explore the role of HDL in arterial inflammation, we profiled the abundance of 35 cytokines in plasma and HDL of men and women with and without CAD. We analyzed whole plasma and native HDL isolated using a selected-affinity immunosorption technique from patients who suffered myocardial infarction at an early age ( Results: Of 35 cytokines analyzed, 25 appear to be significantly transported in HDL. Three cytokines (IL-12, MCP-1, and IL-RA) are excluded from HDL and are only detectable in plasma. IL-3 and IL-7 are predominately associated with HDL and are elevated in both males and females with MI. There are differences in several HDL-associated cytokines that appear to be sex-dependent. Conclusions: We have discovered that a number of cytokines are transported in HDL complexes. Significant elevations or decreases in a number of these cytokines are observed in patients with CAD, and vary in abundance between males and females.

Objectives— The purpose of this study was to identify genetic variants associated with severe coronary artery disease (CAD). Methods and Results— We used 3 case-control studies of white subjects whose severity of CAD was assessed by angiography. The first 2 studies were used to generate hypotheses that were then tested in the third study. We tested 12 077 putative functional single nucleotide polymorphisms (SNPs) in Study 1 (781 cases, 603 controls) and identified 302 SNPs nominally associated with severe CAD. Testing these 302 SNPs in Study 2 (471 cases, 298 controls), we found 5 (in LPA , CALM1 , HAP1 , AP3B1 , and ABCG2 ) were nominally associated with severe CAD and had the same risk alleles in both studies. We then tested these 5 SNPs in Study 3 (554 cases, 373 controls). We found 1 SNP that was associated with severe CAD: LPA I4399M (rs3798220). LPA encodes apolipoprotein(a), a component of lipoprotein(a). I4399M is located in the protease-like domain of apolipoprotein(a). Compared with noncarriers, carriers of the 4399M risk allele (2.7% of controls) had an adjusted odds ratio for severe CAD of 3.14 (confidence interval 1.51 to 6.56), and had 5-fold higher median plasma lipoprotein(a) levels ( P =0.003). Conclusions— The LPA I4399M SNP is associated with severe CAD and plasma lipoprotein(a) levels.

Objectives— Identify gene variants associated with early-onset myocardial infarction (MI). Methods and Results— We tested 11 647 single-nucleotide polymorphisms (SNPs) for association with early-onset MI in a case-control study (study 1 200 cases, 262 controls). To reduce the number of false positives among the 666 SNPs that were nominally associated with early-onset MI ( P P P =0.025; odds ratio [OR], 1.75; CI, 1.17 to 2.62) and an HNRPUL1 variant ( P =0.0043; OR, 1.92; CI, 1.28 to 2.86) were associated with early-onset MI (nominal P Conclusions— Variants in 2 genes were associated with early-onset MI: VAMP8, which is involved in platelet degranulation, and HNRPUL1, which encodes a ribonuclear protein. The identification of these variants could improve understanding of disease mechanisms and suggest novel drug targets.

Background— Hyperlipidemia is associated with endothelial dysfunction, an early event in atherosclerosis and predictor of risk for future coronary artery disease. Epidemiological studies suggest that increased dietary intake of antioxidants reduces the risk of coronary artery disease. The purpose of this study was to determine whether antioxidant vitamin therapy improves endothelial function and affects surrogate biomarkers for oxidative stress and inflammation in hyperlipidemic children. Methods and Results— In a randomized, double-blind, placebo-controlled trial, the effects of antioxidant vitamins C (500 mg/d) and E (400 IU/d) for 6 weeks and the National Cholesterol Education Program Step II (NCEP-II) diet for 6 months on endothelium-dependent flow-mediated dilation (FMD) of the brachial artery were examined in 15 children with familial hypercholesterolemia (FH) or the phenotype of familial combined hyperlipidemia (FCH). Antioxidant vitamin therapy improved FMD of the brachial artery compared with baseline ( P 2 -isoprostanes, 8-hydroxy-2′-deoxyguanosine), inflammation (C-reactive protein), or levels of asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide. Conclusions— Antioxidant therapy with vitamins C and E restores endothelial function in hyperlipidemic children. Early detection and treatment of endothelial dysfunction in high-risk children may retard the progression of atherosclerosis.

Background While estrogens protect against coronary artery disease in women, it is unclear whether they influence cardiovascular function in men. The present report describes coronary vascular abnormalities and the lipoprotein profile of a male patient with estrogen insensitivity caused by a disruptive mutation in the estrogen-receptor gene. Methods and Results Stress thallium scintigraphy, echocardiography, and electron-beam computed tomography (CT) scanning of the coronary arteries and detailed lipoprotein analysis were performed. Electron-beam CT scanning of the coronary arteries showed calcium in the left anterior descending artery. Lipoprotein analysis showed relatively low levels of total (130 mg/dL), LDL (97 mg/dL), and HDL (34 mg/dL) cholesterol; apolipoprotein A-I (91.7 mg/dL;); and lipoprotein(a) (4.1 nmol/L), but normal levels of triglycerides (97 mg/dL) and pre-β-1-HDL cholesterol (61 μg/mL). Conclusions The absence of functional estrogen receptors may be a novel risk factor for coronary artery disease in men.

We used the low molecular weight form of apolipoprotein B (B-48) as a marker for the identification of remnant particles formed from chylomicrons in the plasma of patients with familial dysbetalipoproteinemia. In the serum of patients fasted 14 hours, the d less than 1.006 g/cm3 lipoproteins of prebeta mobility, separated by starch block electrophoresis, contained only the primary hepatogenous species of apolipoprotein B (B-100), and their lipid composition resembled that of normal prebeta very low density lipoproteins. In contrast, the fraction with beta mobility contained both the B-48 and B-100 proteins; the B-48 protein was found primarily among the largest particles. All fractions of beta mobility were greatly enriched with cholesteryl esters. The beta fraction thus contains remnant particles which appear to originate both from chylomicrons and hepatogenous very low density lipoproteins. It appears that these remnant particles share a common removal mechanism which is impaired in familial dysbetalipoproteinemia.