High levels of Lp(a) with a small apo(a) isoform are associated with coronary artery disease in African American and white men

The apolipoprotein(a) size polymorphism is associated with nephrotic syndrome

BACKGROUND

The atherogenic serum lipoprotein(a) [Lp(a)] is significantly elevated in patients with nephrotic syndrome. The underlying mechanism for this elevation is poorly understood.

METHODS

We investigated in 207 patients with nondiabetic nephrotic syndrome and 274 controls whether the apolipoprotein(a) [apo(a)] kringle-IV repeat polymorphism explains the elevated Lp(a) levels in these patients.

RESULTS

Patients showed a tremendous elevation of Lp(a) concentrations when compared to controls (mean 60.4 vs. 20.0 mg/dL and median 29.8 vs. 6.4 mg/dL, P < 0.0001). Primary and secondary causes contributed to this elevation. The primary causes became apparent by a markedly elevated number of low-molecular-weight apo(a) phenotypes which are usually associated with high Lp(a) levels. This frequency was 35.7% in patients compared to only 24.8% in controls (P= 0.009). In addition, secondary causes by the pathogenetic mechanisms of the nephrotic syndrome itself resulted in a different increase of Lp(a) in the various apo(a) isoform groups. Based on the measured Lp(a) concentrations in each subject, we calculated separately the Lp(a) concentrations arising from the two expressed isoforms by estimating the relative proportion of the two serum isoforms in the sodium dodecyl sulfate (SDS) agarose gel electrophoresis. Low-molecular-weight isoforms were associated with 40% to 75% elevated Lp(a) concentrations when compared to matched isoforms from controls. High-molecular-weight apo(a) isoforms showed 100% to 500% elevated Lp(a) levels compared to matched isoforms from controls. The severity of the nephrotic syndrome as well as the degree of renal impairment did not influence the Lp(a) concentrations.

CONCLUSION

The tremendously increased Lp(a) levels in nephrotic syndrome ar caused by primary genetic as well as disease-related mechanisms.

Ability of non-high-density lipoprotein cholesterol and calculated intermediate-density lipoprotein to identify nontraditional lipoprotein subclass risk factors in dialysis patients

BACKGROUND

Non-high-density lipoprotein cholesterol (non-HDL-C) and calculated intermediate-density lipoprotein cholesterol (IDL-C) have been proposed as surrogate markers to estimate apolipoprotein B-containing lipoproteins. The purpose of this study was to determine the validity of non-HDL-C and calculated IDL-C to predict nontraditional lipoprotein risk factors among dialysis patients and to compare the prevalence of these nontraditional risk factors between dialysis modalities.

METHODS

The authors performed a cross-sectional analysis comparing standard lipid profile with lipoprotein analysis via nuclear magnetic resonance (NMR) spectroscopy among 186 hemodialysis (HD) and peritoneal dialysis (PD) patients on modern lipid-lowering therapy.

RESULTS

The PD group had a significantly higher low-density lipoprotein (LDL) particle concentration (P < 0.005), higher large very low-density lipoprotein (VLDL; P < 0.001), greater small dense LDL (P < 0.001), and lower protective large HDL (P < 0.005). Forty-six (40%) of 118 subjects with LDL-C below goal had at least 1 nontraditional risk factor by NMR spectroscopy. The sensitivity of non-HDL-C method together with triglyceride (TG) value greater than 200 mg/dL (>2.26 mmol/L) to predict nontraditional risk was 13% and increased to 20% if TG values were excluded. A negative correlation was observed between LDL particle size and HDL-C (r2 = 0.269; P < 0.001); the sensitivity of HDL-C to predict LDL size was 92%. There was no relationship between measured IDL by NMR and calculated IDL-C (r2 = 0.005; P = 0.69).

CONCLUSION

Non-HDL-C greater than 130 mg/dL (3.4 mmol/L) independent of TG values and HDL-C lower than 40 mg/dL (1.0 mmol/L) may predict nontraditional lipoprotein risk factors among dialysis patients. This is especially applicable to patients on PD, a modality associated with a more atherogenic lipoprotein profile.

Plasma lipoprotein concentrations in ethnic populations

There is a complex interplay between genetic and environmental factors that influences the expression of plasma lipoprotein levels. It is therefore not surprising that differences in lipid levels have been reported between ethnic groups. There are conflicting data on racial and ethnic variations in lipids, and also limited data on the relationship between lipoprotein levels and coronary heart disease risk in specific populations. This review summarizes available data on ethnic variations in plasma lipoproteins and the potential impact on coronary morbidity and mortality.

Lipoprotein (a) and lipid profile in neonates from mothers with three different types of diabetes mellitus

OBJECTIVES

The metabolic components in neonates may be affected by maternal diabetes mellitus.

DESIGN AND METHODS

To investigate the alterations in lipid metabolism and the possible atherogenic risk, the lipoprotein a (Lp a), apoproteins, lipid profile, glucose concentrations were measured (ELISA, immunodiffusion and enzymatic) in 77 cord blood samples from diabetic and healthy pregnant mothers.

RESULTS

The body weight, cord glucose and both apoproteins were increased in neonates of gestational and noninsulin dependent diabetic (GDM, NIDDM) than in neonates of nondiabetic mothers (NNDM). The Lp (a) was not correlated with the blood glucose and didn't significantly increase in the three neonates groups of diabetic mothers. The apo B/apo A1 and the LDL/HDL ratios were insignificantly increased in relation to the body weight. In neonates of diabetic mothers (NDM), only the blood glucose and Lp (a) differ between both sexes.

CONCLUSION

NDM may have disturbed lipid metabolism, which require special care to them and to their mothers during the prenatal period.

Lack of genetic linkage evidence for a trans-acting factor having a large effect on plasma lipoprotein[a] levels in African Americans

The distribution of plasma lipoprotein[a] (Lp[a]) concentrations, a risk factor for cardiovascular disease, varies greatly among racial groups, with African Americans having values that are shifted toward higher levels than those of whites. The underlying cause of this heterogeneity is unknown, but a role for "trans-acting" factors has been hypothesized. This study used genetic linkage analysis to localize genetic factors influencing Lp[a] levels in African Americans that were absent in other populations; linkage results were analyzed separately in non-Hispanic whites, Hispanic whites, and African Americans. As expected, all three samples showed highly significant linkage at the approximate location of the lysophosphatidic acid locus. The white populations also independently had regions of significant linkage on chromosome 19 (LOD 3.80) and suggestive linkage on chromosomes 12 (LOD 1.60), 14 (LOD 2.56), and 19 (LOD 2.52). No linkage evidence was found to support the hypothesis of another single gene with large effects specifically segregating in African Americans that may account for their elevated Lp[a] levels.

Analysis of the apo(a) size polymorphism in Asian Indian populations: association with Lp(a) concentration and coronary heart disease

Most studies aiming to detect associations of genetic variation with common complex diseases, e.g. coronary heart disease (CHD) have been performed in populations with a western lifestyle but it is unclear whether associations detected in one geographic group exist also in others. We here have determined lipoprotein(a) levels and apo(a) K-IV-2 repeat genotypes in CHD patients (N=254) and controls (N=480) from two Asian Indian populations (Tamil Nadu and New Delhi). In both populations and also in the pooled dataset median Lp(a) levels were significantly elevated in the patients (27.4 mg/dl) compared with the controls (17.6 mg/dl). Apo(a) K-IV-2 allele frequencies were not different between the CHD patients and controls and thus did not explain the increased Lp(a) levels in CHD patients. Contrary to what has recently been observed in Black and White men short (K-IV<or=22) alleles associated with high Lp(a) concentration were not overrepresented in the patients. Rather, short (K-IV<or=22), intermediate (K-IV 23-29) and long (K-IV>or=30) apo(a) alleles were all associated with higher Lp(a) levels in the patients. Accordingly relative risk (estimated as odds ratio) for CHD rose continuously with increasing Lp(a) but was independent of apo(a) allele length. Together with previous studies our results indicate that the relation between apo(a) genotypes, Lp(a) levels, and CHD may be heterogeneous across ethnic groups and that it depends on the genetic architecture of the Lp(a) trait in a given population whether an association of K-IV-2 repeat length with CHD exists or not.

Lipoprotein(a), apolipoprotein(a) polymorphism and restenosis after intracoronary stent placement in Type 2 diabetic patients

The relationship between lipoprotein(a) [Lp(a)] and restenosis after intracoronary stent implantation has never been analysed in diabetic patients. The aim of the present prospective study was to evaluate whether Lp(a) levels and apolipoprotein(a) [apo(a)] phenotypes are predictors of restenosis after elective stent implantation in Type 2 diabetic patients with de novo lesions of coronary arteries. We recruited 102 Type 2 diabetic patients with a new lesion successfully treated with elective placement of one or two Palmaz-Schatz stents. Follow-up angiography was scheduled at 6 months or earlier if clinically indicated. Seven patients were lost to the follow up. Among 95 patients enrolled, restenosis was present in 37 (38.9%) and absent in 58 (61.1%). The restenosis group showed Lp(a) levels higher than the nonrestenosis group (25.1+/-14.4 vs. 21.3+/-14.6 mg/dl), but the difference was not significant. The restenosis group had a percentage of subjects with at least one apo(a) isoform of low molecular weight (MW) significantly greater than the nonrestenosis group (75.7% vs. 55.1%; P<.05). A multiple logistic regression analysis showed that presence of multivessel disease (risk relative [RR]: 5.83; 95% confidence interval [CI]: 1.21-28.15; P<.05) was the only predictor of restenosis after stent placement in diabetic patients. Lp(a) and apo(a) polymorphisms did not enter the model as predictive variables. Our study shows that the presence of multivessel disease is a predictor of restenosis after intracoronary stent implantation in diabetic patients. On the contrary, Lp(a) and apo(a) polymorphisms do not appear to be reliable markers of restenosis in patients with Type 2 diabetes mellitus.

Study of apo(a) length polymorphism and lipoprotein(a) concentrations in subjects with single or double apo(a) isoforms

Cardiovascular risk is associated with high lipoprotein(a) (Lp(a)) concentrations and low molecular weight apolipoprotein(a) (apo(a)) isoforms. We studied the relationship between these two biological parameters, particularly in subjects expressing two apo(a) isoforms. Plasma Lp(a) was measured by immunonephelometry in 530 unrelated Caucasian patients at high cardiovascular risk, and apo(a) size determined by immunoblotting using a recombinant standard. Two, one, or no apo(a) isoforms were detected in 258, 270, and 2 subjects, respectively. Lp(a) concentrations showed a non-Gaussian distribution, being higher in the 'double band' than in the 'single band' group (median 0.42 vs. 0.11 g/l, p < 0.0005). Apo(a) size distribution was bimodal, with two frequency peaks at 18 kringles (K) and 27 K. Small size apo(a) isoforms were more frequently found in the 'double band' group, where major isoforms were of lower size than minor isoforms (median 20 vs. 27 K). Regression analysis showed that apo(a) gene length accounted for 33% of Lp(a) variation, with a threshold effect at 20 K, no correlation being found over this value. The minor apo(a) isoform did not significantly influence Lp(a) concentration. These data confirm the relationship between apo(a) size and Lp(a) concentration and suggest that the assessment of cardiovascular risk should take into account the threshold effect at 20 K and the absence of influence of the minor apo(a) isoform.

Factors contributing to variation in lipoprotein (a) in Melbourne Anglo-Celtic population

AIM

The purpose of this report is to survey the factors contributing to variation in lipoprotein(a) (Lp(a)) in a population-based sample of Anglo-Celtic Melburnians.

RESULTS

The plasma Lp(a) levels were highly skewed towards low levels in this population, with a median of 156 mg/l and a mean of 262 mg/l. Approximately 33% had plasma Lp(a) above the threshold value of 300 mg/l, while 35% had Lp(a) levels below 100 mg/l. The most commonly occurring phenotype was apo(a) S3. In this phenotype, Lp(a) concentrations ranged from 10 to 596 mg/l. Lp(a) was consistently associated with diastolic blood pressure, systolic blood pressure, total protein, albumin and nitrogen excretion in the 40-60 y age group. Multiple stepwise regression analyses, in non-dietary factors, were used to explain about 13% of the variance in Lp(a) (19% in men and 23% in women). Remarkably, in the <40 y age group, non-dietary factors may account for 86% of the variance in Lp(a) and dietary factors, analysed separately, 46%. Thus, although Lp(a) is mainly genetically determined, there are clearly other factors which contribute to variations in Lp(a) concentrations.

Lipoprotein(a): an emerging cardiovascular risk factor

Lipoprotein(a) is a cholesterol-enriched lipoprotein, consisting of a covalent linkage joining the unique and highly polymorphic apolipoprotein(a) to apolipoprotein B100, the main protein moiety of low-density lipoproteins. Although the concentration of lipoprotein(a) in humans is mostly genetically determined, acquired disorders might influence synthesis and catabolism of the particle. Raised concentration of lipoprotein(a) has been acknowledged as a leading inherited risk factor for both premature and advanced atherosclerosis at different vascular sites. The strong structural homologies with plasminogen and low-density lipoproteins suggest that lipoprotein(a) might represent the ideal bridge between the fields of atherosclerosis and thrombosis in the pathogenesis of vascular occlusive disorders. Unfortunately, the exact mechanisms by which lipoprotein(a) promotes, accelerates, and complicates atherosclerosis are only partially understood. In some clinical settings, such as in patients at exceptionally low risk for cardiovascular disease, the potential regenerative and antineoplastic properties of lipoprotein(a) might paradoxically counterbalance its athero-thrombogenicity, as attested by the compatibility between raised plasma lipoprotein(a) levels and longevity.

Restenosis after intracoronary stent placement: can apolipoprotein(a) polymorphism play a role?

BACKGROUND

The relationship between lipoprotein(a) and restenosis after intracoronary stent implantation has been analysed by two specific studies, but the role of apoliprotein(a) polymorphism was not considered. The aim of the present prospective study was to evaluate whether lipoprotein(a) levels and apolipoprotein(a) phenotypes are predictors of restenosis after elective stent implantation in patients with de novo lesions of coronary arteries.

METHODS

We recruited 182 patients with a new lesion successfully treated with elective placement of one or two Palmaz-Schatz stents. Follow-up angiography was scheduled at 6 months or earlier if clinically indicated. Nine patients were lost to the follow up. Among 173 patients enrolled, restenosis was present in 52 (30.0%) and absent in 121 (70.0%).

RESULTS

Lipoprotein(a) levels were higher in the restenosis than in the nonrestenosis group (29.5+/-17.2 versus 27.4+/-20.2 mg/dl), even if the difference did not attain statistical significance (P=0.067). The restenosis group had a percentage of subjects with at least one apolipoprotein(a) isoform of low molecular weight significantly greater than the nonrestenosis group (82.7 versus 66.9%; P=0.035). A multiple logistic regression analysis showed that multiple stenting (RR: 4.01; CI 95%: 1.65-13.91; P=0.004), presence of diabetes (RR: 3.96; CI 95%: 1.67-9.37; P=0.002) and presence of multivessel disease (RR: 2.71; CI 95%: 1.19-6.16; P=0.017) were predictors of restenosis after stent placement. Lipoprotein(a) and apolipoprotein(a) polymorphism did not enter the model as predictive variables.

CONCLUSIONS

Our study confirms that multiple stenting, diabetes and multivessel disease are powerful predictors of restenosis after intracoronary stent implantation. On the contrary, lipoprotein(a) and apolipoprotein(a) polymorphism do not appear to be reliable markers of restenosis in patients with stent implantation.

Silent coronary artery disease in type 2 diabetes mellitus: the role of Lipoprotein(a), homocysteine and apo(a) polymorphism

BACKGROUND

There is little data on the relationship between novel cardiovascular risk factors and silent coronary artery disease (CAD) in diabetic patients. We investigated whether Lipoprotein(a), homocysteine and apolipoprotein(a) polymorphism are associated with angiographically assessed asymptomatic coronary artery disease (CAD) in diabetic patients.

METHODS

1,971 type 2 diabetic patients without clinical signs of cardiovascular diseases and with a negative history of CAD were consecutively evaluated. Among them, 179 patients showed electrocardiographic abnormalities suggestive of ischemia or previous asymptomatic myocardial infarction. These 179 patients were subjected to a non-invasive test for CAD (ECG stress testing and/or scintigraphy). Among patients with a highly positive stress testing (n = 19) or a positive scintigraphy (n = 74), 75 showed an angiographically documented CAD (CAD group). Seventy-five patients without CAD (NO CAD group) were matched by age, sex and duration of diabetes to CAD patients. In NO CAD patients an exercise ECG test, a 48-hour ambulatory ECG and a stress echocardiogram were negative for CAD.

RESULTS

Lipoprotein(a) levels (22.0 +/- 18.9 versus 16.0 +/- 19.4 mg/dl; p < 0.05), homocysteine levels (13.6 +/- 6.6 versus 11.4 +/- 4.9 mmol/l; p < 0.05) and the percentage of subjects with at least one small apolipoprotein(a) isoform (70.7% versus 29.3%; p < 0.0001) were higher in CAD than NO CAD group. Logistic regression analysis showed that apolipoprotein(a) polymorphism (OR:8.65; 95%CI:3.05-24.55), microalbuminuria (OR:6.16; 95%CI:2.21-17.18), smoking (OR:2.53; 95%CI:1.05-6.08), HDL (OR:3.16; 95%CI:1.28-7.81), homocysteine (OR:2.25; 95%CI:1.14-4.43) and Lipoprotein(a) (OR:2.62; 95%CI:1.01-6.79) were independent predictors of asymptomatic CAD.

CONCLUSIONS

The present investigation shows an independent association of Lipoprotein(a), homocysteine and apo(a) polymorphism with silent CAD. Other studies are needed to establish whether these parameters are suitable for CAD screening in diabetic patients.

Assessment of asymptomatic coronary artery disease in apparently uncomplicated type 2 diabetic patients: a role for lipoprotein(a) and apolipoprotein(a) polymorphism

OBJECTIVE

In patients with uncomplicated diabetes, there is low probability of finding significant coronary artery disease (CAD) by noninvasive tests. Therefore, screening for its presence is not justified, and it is important to find reliable predictors of silent CAD to identify patients with uncomplicated diabetes for further screening. The relationship between lipoprotein(a) [Lp(a)], apolipoprotein(a) [apo(a)] polymorphism, and silent CAD has never been studied. We investigated the association of Lp(a) and apo(a) polymorphism with angiographically documented asymptomatic CAD in type 2 diabetic patients without evident complications.

RESEARCH DESIGN AND METHODS

A total of 1,323 diabetic patients without any clinical and electrocardiographic evidence of CAD were evaluated. Of 121 patients with highly positive results of exercise electrocardiography (ECG) (n = 30) or positive results on exercise thallium scintigraphy (n = 91), 103 subjects showed angiographically documented CAD (CAD group). Of 1,106 patients with negative results on exercise ECG, 103 subjects without CAD (NO CAD group) were selected and matched by age, gender, and duration of diabetes to patients in the CAD group. In patients in the NO CAD group, results of exercise ECG, 48-h ambulatory ECG, and stress echocardiography were negative for CAD.

RESULTS

The CAD group had higher Lp(a) levels (21.7 +/- 17.7 vs. 15.2 +/- 19.0 mg/dl; P = 0.0093) than the NO CAD group, and a percentage of subjects had at least one small apo(a) isoform (68.9 vs. 29.1%; P = 0.0000) higher than the NO CAD group. Logistic regression analysis showed that apo(a) phenotypes (odds ratio [OR] 8.13, 95% CI 3.65-21.23), microalbuminuria (5.38, 2.44-11.88), smoking (2.72, 1.31-5.64), and Lp(a) levels (2.41, 1.15-5.03) were predictors of asymptomatic CAD.

CONCLUSIONS

Our investigation reports the first evidence of an independent association of Lp(a) and apo(a) polymorphism with asymptomatic CAD. This suggests that Lp(a) levels and apo(a) phenotypes could be used together with other risk factors as markers of asymptomatic CAD in patients with diabetes.

The role of non-LDL:non-HDL particles in atherosclerosis

Elevated concentrations of circulating apolipoprotein B (apoB)-containing lipoproteins, other than low-density lipoprotein (LDL), have been implicated as causative agents for the development of atherosclerosis. A form of dyslipidemia, the atherogenic lipoprotein profile, that consists of elevated intermediate-density lipoprotein (IDL), triglycerides (TGs), dense LDL and dense very low density lipoprotein (VLDL), and low high density lipoprotein-2, occurs in 40% to 50% of patients with coronary artery disease (CAD). The recently released Adult Treatment Panel III guidelines suggest that because elevated TGs are an independent CAD risk factor, some TG-rich lipoproteins, commonly called remnant lipoproteins, must be atherogenic. Relevant to this series on diabetes, a number of studies have shown that in type 2 diabetes, the severity of CAD is positively related to the numbers of TG-rich particles in the plasma. Although less clear, other studies in type 2 diabetes suggest that elevated levels of lipoprotein (a) [Lp(a)] may also be independently associated with CAD. In this article, we summarize evidence for the role of apoB-containing lipoprotein particles other than LDL in the development of atherosclerosis and discuss methods of quantification and possible pharmacologic interventions for lowering their plasma concentrations. The particles reviewed include the TG-rich lipoproteins: VLDL and its remnants, chylomicron remnants and IDL, and the C-rich lipoprotein: Lp(a).

Heterozygous apolipoprotein (a) status and protein expression as a risk factor for premature coronary heart disease

Exactly how apolipoprotein a [APO(a)] isoform size affects the degree of cardiovascular risk associated with high lipoprotein a [LP(a)] levels is not fully understood. Using a sodium dodecyl sulfate-agarose APO(a) & LP(a) phenotyping method, we assessed the role of APO(a) size heterogeneity according to the number of kringle 4 repeats and the differential APO(a) protein expression in 91 male Spanish patients with premature coronary heart disease (CHD) compared with 99 healthy Spanish men. CHD patients had significantly increased median plasma LP(a) levels (0.31 g/L) and a higher percentage of subjects with LP(a) levels of 0.30 g/L or greater (51%) than controls (0.15 g/L and 23%, respectively). Patients with the double-band phenotype had significantly higher plasma LP(a) levels (median 0.37 g/L) compared with those expressing a single-band phenotype (median 0.20 g/L; P =.018) and with their corresponding controls (median 0.15 g/L; P <.001). The double-band phenotype and LP(a) values of 0.30 g/L or greater had a significant association with CHD (odds ratio [OR] 6.47, 95% confidence interval [CI] 2.51-16.7), stronger than that observed for the entire group (OR 4.19, 95% CI 1.97-8.90). The adjusted OR for the APO(a) protein pattern that equally expressed both isoforms indicates an independent association with premature CHD (OR 3.33; 95% CI 1.08-10.3). These results suggest that APO(a) phenotyping might be used in subjects with hyperlipoproteinemia a as a powerful marker to assess the risk of premature CHD because heterozygous status, mainly when both isoforms are equally expressed, is associated with higher cardiovascular risk.

Fluorescence-based, Nonradioactive Method for Efficient Detection of the Pentanucleotide Repeat (TTTTA)n Polymorphism in the Apolipoprotein(a) Gene

Background: The apolipoprotein(a) [apo(a)] gene is a major predictor of plasma lipoprotein(a) concentrations, an independent risk factor for cardiovascular disease. The apo(a) gene contains a pentanucleotide repeat (PNR) polymorphism, 1.4 kb upstream from the apo(a) gene reading frame. This polymorphism has been suggested to be important in control of apo(a) gene expression.

Methods: We developed a fluorescence-based, nonradioactive procedure to detect the PNR polymorphism. After amplification of the polymorphism by PCR, the respective PCR products were separated by denaturing polyacrylamide gel electrophoresis and detected using a 3′-end fluorescently labeled oligonucleotide as a probe. We used the method to characterize the PNR polymorphism pattern in 313 individuals, 195 Caucasians and 118 African Americans. The new method efficiently separated DNAs corresponding to the different PNR repeats.

Results: Among both ethnic groups, alleles containing eight PNRs were most common. Smaller PNRs were more common among African Americans, and larger PNRs were more common among Caucasians.

Conclusions: We developed a nonradioactive technique that separates the PNR polymorphism in the apo(a) gene and can be used in other studies involving closely sized polymorphisms.

Clinical trials: surrogate endpoints or hard endpoints?

A man, aged 50, has about a 50% risk and a 50-year-old woman a 35% risk of having a myocardial infarction during their lifetime. The extent of atherosclerosis is the primary determinant of the risk of myocardial infarction. We will be unable to substantially reduce the lifetime risk of coronary artery disease without primary prevention of atherosclerosis. Noninvasive methods to measure subclinical atherosclerosis and its progression offer a unique opportunity to improve individual patient preventive strategies, based both on pharmacologic and nonpharmacologic therapies, as well as an opportunity to study and develop new drug therapies. The use of subclinical disease as a surrogate marker of atherosclerosis and the study of plaque characteristics will greatly enhance our understanding of the role of new risk factors for atherosclerosis, lipoprotein metabolism, and genetic-lifestyle interactions.