Simplified Canadian Definition for Familial Hypercholesterolemia.

Familial hypercholesterolemia (FH) is an autosomal codominant lipoprotein disorder characterized by elevated low-density lipoprotein cholesterol (LDL-C) and high risk of premature atherosclerotic cardiovascular disease. Definitions for FH rely on complex algorithms that are on the basis of levels of total or LDL-C, clinical features, family history, and DNA analysis that are often difficult to obtain. We propose a novel simplified definition for FH. Definite FH includes: (1) elevated LDL-C (≥ 8.50 mmol/L); or (2) LDL-C ≥ 5.0 mmol/L (for age 40 years or older; ≥ 4.0 mmol/L if age younger than 18 years; and ≥ 4.5 mmol/L if age is between 18 and 39 years) when associated with at least 1 of: (1) tendon xanthomas; or (2) causal DNA mutation in the LDLR, APOB, or PCSK9 genes in the proband or first-degree relative. Probable FH is defined as subjects with an elevated LDL-C (≥ 5.0 mmol/L) and the presence of premature atherosclerotic cardiovascular disease in the patient or a first-degree relative or an elevated LDL-C in a first-degree relative. LDL-C cut points were determined from a large database comprising > 3.3 million subjects. To compare the proposed definition with currently used algorithms (ie, the Simon Broome Register and Dutch Lipid Clinic Network), we performed concordance analyses in 5987 individuals from Canada. The new FH definition showed very good agreement compared with the Simon Broome Register and Dutch Lipid Clinic Network criteria (κ = 0.969 and 0.966, respectively). In conclusion, the proposed FH definition has diagnostic performance comparable to existing criteria, but adapted to the Canadian population, and will facilitate the diagnosis of FH patients.

Effect of Rosuvastatin on Carotid Intima-Media Thickness in Children With Heterozygous Familial Hypercholesterolemia: The CHARON Study (Hypercholesterolemia in Children and Adolescents Taking Rosuvastatin Open Label).

BACKGROUND: Heterozygous familial hypercholesterolemia (HeFH) is an autosomal dominant disorder leading to premature atherosclerosis. Children with HeFH exhibit early signs of atherosclerosis manifested by increased carotid intima-media thickness (IMT). In this study, we assessed the effect of 2-year treatment with rosuvastatin on carotid IMT in children with HeFH. METHODS: Children with HeFH (age, 6-<18 years) and low-density lipoprotein cholesterol >4.9 mmol/L or >4.1 mmol/L in combination with other risk factors received rosuvastatin for 2 years, starting at 5 mg once daily, with uptitration to 10 mg (age, 6-<10 years) or 20 mg (age, 10-<18 years). Carotid IMT was assessed by ultrasonography at baseline and 12 and 24 months in all patients and in age-matched unaffected siblings. Carotid IMT was measured at 3 locations (common carotid artery, carotid bulb, internal carotid artery) in both the left and right carotid arteries. A linear mixed-effects model was used to evaluate differences in carotid IMT between children with HeFH and the unaffected siblings. P values were adjusted for age, sex, carotid artery site, and family relations. RESULTS: At baseline, mean±SD carotid IMT was significantly greater for the 197 children with HeFH compared with the 65 unaffected siblings (0.397±0.049 and 0.377±0.045 mm, respectively; P=0.001). During 2 years of follow-up, the change in carotid IMT was 0.0054 mm/y (95% confidence interval, 0.0030-0.0082) in children with HeFH and 0.0143 mm/y (95% confidence interval, 0.0095-0.0192) in unaffected siblings (P=0.002). The end-of-study difference in mean carotid IMT between children with HeFH and unaffected siblings after 2 years was no longer significant (0.408±0.043 and 0.402±0.042 mm, respectively; P=0.2). CONCLUSIONS: In children with HeFH who were ≥6 years of age, carotid IMT was significantly greater at baseline compared with unaffected siblings. Rosuvastatin treatment for 2 years resulted in significantly less progression of increased carotid IMT in children with HeFH than untreated unaffected siblings. As a result, no difference in carotid IMT could be detected between the 2 groups after 2 years of rosuvastatin. These findings support the value of early initiation of statin treatment for low-density lipoprotein cholesterol reduction in children with HeFH. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01078675.

Efficacy and safety of rosuvastatin therapy in children and adolescents with familial hypercholesterolemia: Results from the CHARON study.

OBJECTIVE: Heterozygous familial hypercholesterolemia (HeFH) is an autosomal dominant disorder leading to premature atherosclerosis. Guidelines recommend initiating statins early to reduce low-density lipoprotein cholesterol (LDL-C). Studies have evaluated rosuvastatin in children aged ≥10 years, but its efficacy and safety in younger children is unknown. METHODS: Children with HeFH and fasting LDL-C >4.92 mmol/L (190 mg/dL) or >4.10 mmol/L (>158 mg/dL) with other cardiovascular risk factors received rosuvastatin 5 mg daily. Based on LDL-C targets (<2.85 mmol/L [<110 mg/dL]), rosuvastatin could be uptitrated to 10 mg (aged 6-9 years) or 20 mg (aged 10-17 years). Treatment lasted 2 years. Changes in lipid values, growth, sexual maturation, and adverse events (AEs) were assessed. RESULTS: The intention-to-treat analysis included 197 patients. At 24 months, LDL-C was reduced by 43, 45, and 35% vs baseline in patients aged 6-9, 10-13, and 14-17 years, respectively (P < .001 for all groups). Most AEs were mild. Intermittent myalgia was reported in 11 (6%) patients and did not lead to discontinuation of rosuvastatin treatment. Serious AEs were reported by 9 (5%) patients, all considered unrelated to treatment by the investigators. No clinically important changes in hepatic biochemistry were reported. Rosuvastatin treatment did not appear to adversely affect height, weight, or sexual maturation. CONCLUSIONS: In HeFH patients aged 6-17 years, rosuvastatin 5-20 mg over 2 years significantly reduced LDL-C compared with baseline. Treatment was well tolerated, with no adverse effects on growth or sexual maturation.

Efficacy and safety of ezetimibe monotherapy in children with heterozygous familial or nonfamilial hypercholesterolemia.

OBJECTIVES: To evaluate the lipid-altering efficacy and safety of ezetimibe monotherapy in young children with heterozygous familial hypercholesterolemia (HeFH) or nonfamilial hypercholesterolemia (nonFH). STUDY DESIGN: One hundred thirty-eight children 6-10 years of age with diagnosed HeFH or clinically important nonFH (low-density lipoprotein cholesterol [LDL-C] ≥ 160 mg/dL [4.1 mmol/L]) were enrolled into a multicenter, 12-week, randomized, double-blind, placebo-controlled study. Following screening/drug washout and a 5-week single-blind placebo-run-in with diet stabilization, subjects were randomized 2:1 to daily ezetimibe 10 mg (n = 93) or placebo (n = 45) for 12 weeks. Lipid-altering efficacy and safety were assessed in all treated patients. RESULTS: Overall, mean age was 8.3 years, 57% were girls, 80% were white, mean baseline LDL-C was 228 mg/dL (5.9 mmol/L), and 91% had HeFH. After 12 weeks, ezetimibe significantly reduced LDL-C by 27% after adjustment for placebo (P < .001) and produced significant reductions in total cholesterol (21%), nonhigh-density lipoprotein cholesterol (26%), and apolipoprotein B (20%) (P < .001 for all). LDL-C lowering response in sex, race, baseline lipids, and HeFH/nonFH subgroups was generally consistent with overall study results. Ezetimibe was well tolerated, with a safety profile similar to studies in older children, adolescents, and adults. CONCLUSIONS: Ezetimibe monotherapy produced clinically relevant reductions in LDL-C and other key lipid variables in young children with primary HeFH or clinically important nonFH, with a favorable safety/tolerability profile. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00867165.

Design and baseline data of a pediatric study with rosuvastatin in familial hypercholesterolemia.

BACKGROUND: Statin therapy is recommended for children with familial hypercholesterolemia (FH), but most children do not reach treatment targets. OBJECTIVE: Here we present the design and results at baseline of the ongoing CHARON study, to evaluate the safety and efficacy of rosuvastatin. METHODS: This study comprises an international 2-year open label, titration-to-goal study in 198 children with heterozygous FH aged 6 to 18 years, with rosuvastatin in a maximum dose of 10 mg (<10 years of age) or 20 mg (older children). In addition, 64 unaffected siblings were enrolled as controls. The primary efficacy outcome is the change from baseline in low-density lipoprotein cholesterol, and the secondary outcome is the change in carotid intima-media thickness (c-IMT) in patients with FH compared with their siblings. The primary safety outcomes are growth and sexual maturation; secondary outcomes are the change in other lipoprotein levels and the incidence of adverse events, discontinuation rates, and abnormal laboratory values. RESULTS: At baseline, mean age of patients with FH was 12.1 ± 3.3 years, 44% were boys, and mean low-density lipoprotein cholesterol levels were 6.1 ± 1.3 mmol/L (235.9 ± 48.7 mg/dL). Mean c-IMT was 0.399 mm (95% CI, 0.392-0.406 mm) in children with FH versus 0.377 (95% CI, 0.366-0.388 mm) in unaffected siblings (P = .001). CONCLUSIONS: At baseline, as expected according to on previous observations, children with FH proved to have a greater c-IMT than their healthy siblings. These differences had already occurred at a very young age, which emphasizes the importance of considering early statin initiation in this high-risk population.

Apolipoprotein B synthesis inhibition with mipomersen in heterozygous familial hypercholesterolemia: results of a randomized, double-blind, placebo-controlled trial to assess efficacy and safety as add-on therapy in patients with coronary artery disease.

BACKGROUND: Heterozygous familial hypercholesterolemia (HeFH) is a common genetic disorder leading to premature coronary artery disease. Despite statins and additional lipid-lowering therapies, many HeFH patients fail to achieve low-density lipoprotein cholesterol (LDL-C) goals. We evaluated mipomersen, an apolipoprotein B synthesis inhibitor, to further lower LDL-C in HeFH patients with coronary artery disease. METHODS AND RESULTS: This double-blind, placebo-controlled, phase 3 trial randomized patients with HeFH and coronary artery disease on maximally tolerated statin and LDL-C ≥2.6 mmol/L (≥100 mg/dL) to weekly subcutaneous mipomersen 200 mg or placebo (2:1) for 26 weeks. The primary end point was percent change in LDL-C from baseline at week 28. Safety assessments included adverse events, laboratory tests, and magnetic resonance imaging assessment of hepatic fat. Of 124 randomized patients (41 placebo, 83 mipomersen), 114 (41 placebo, 73 mipomersen) completed treatment. Mean (95% confidence interval) LDL-C decreased significantly with mipomersen (-28.0% [-34.0% to -22.1%] compared with 5.2% [-0.5% to 10.9%] increase with placebo; P<0.001). Mipomersen significantly reduced apolipoprotein B (-26.3%), total cholesterol (-19.4%), and lipoprotein(a) (-21.1%) compared with placebo (all P<0.001). No significant change occurred in high-density lipoprotein cholesterol. Adverse events included injection site reactions and influenza-like symptoms. Five mipomersen patients (6%) had 2 consecutive alanine aminotransferase values ≥3 times the upper limit of normal at least 7 days apart; none were associated with significant bilirubin increases. Hepatic fat content increased a median of 4.9% with mipomersen versus 0.4% with placebo (P<0.001). CONCLUSIONS: Mipomersen is an effective therapy to further reduce apolipoprotein B-containing lipoproteins, including LDL and lipoprotein(a), in HeFH patients with coronary artery disease on statins and other lipid-lowering therapy. The significance of hepatic fat and transaminase increases remains uncertain at this time. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00706849.

Clinical and molecular characterization of a severe form of partial lipodystrophy expanding the phenotype of PPARγ deficiency.

Familial partial lipodystrophy (FPLD) is characterized by abnormal fat distribution and a metabolic syndrome with hypertriglyceridemia. We identified a family with a severe form of FPLD3 with never-reported clinical features and a novel mutation affecting the DNA binding domain of PPARγ (E157D). Apart from the lipodystrophy and severe metabolic syndrome, individuals presented musculoskeletal and hematological issues. E157D heterozygotes had a muscular habitus yet displayed muscle weakness and myopathy. Also, E157D heterozygotes presented multiple cytopenias and a susceptibility to autoimmune disease. In vitro studies showed that the E157D mutation does not decrease the receptor's affinity to classical PPAR response elements or its responsiveness to a PPARγ agonist, yet it severely reduces its target gene transcription. Microarray experiments demonstrated a decreased activation of a wide array of genes, including genes involved in the PPAR response, the immune response, hematopoiesis, and metabolism in muscle. In addition, a subset of genes with cryptic PPAR response elements was activated. In summary, we describe a large family with a novel PPARγ mutation, which extends the clinical phenotype of FPLD3 to include muscular, immune, and hematological features. Together, our results support the role of PPARγ in controlling homeostasis of multiple systems beyond lipid metabolism.

Carotid atherosclerosis progression in familial hypercholesterolemia patients: a pooled analysis of the ASAP, ENHANCE, RADIANCE 1, and CAPTIVATE studies.

BACKGROUND: Until recently, patients with heterozygous familial hypercholesterolemia (HeFH) were considered the best subjects for the assessment of changes in carotid intima-media thickness (cIMT) in randomized intervention trials. Our aims were to investigate whether contemporary statin-treated HeFH patients still show accelerated cIMT increase and to assess the impact of statin treatment, before and after random assignment, on atherosclerosis progression. METHODS AND RESULTS: We retrospectively evaluated cIMT change, and prior statin treatment and postbaseline LDL-C change as predictors of cIMT change, in 1513 HeFH patients who were randomly assigned to the statin arms of the early ASAP and more recent RADIANCE 1, CAPTIVATE, and ENHANCE studies. In the 3 recent studies combined, mean cIMT increased at only 33%of the rate of the simvastatin-treated patients in the ASAP study (0.014 mm/2 years [95% confidence interval, -0.0003-0.028] versus 0.041 mm/2 years [95% confidence interval, 0.020-0.061]; P<0.05). Patients whose statin therapy could be intensified, as evidenced by an LDL-C decrease after the initiation of on-trial statin therapy, showed cIMT decrease in the first 6 to 12 months and a much lower cIMT increase measured over the full 2 years. In line with this, previously statin-naive HeFH patients showed a lower overall cIMT increase. CONCLUSIONS: Over the years, intensification of statin therapy in HeFH patients has resulted in an impressive decrease in carotid atherosclerosis progression. In studies that assess other antiatherosclerotic modalities, statin therapy may still induce rapid changes in cIMT. For future cIMT studies, our analyses suggest that patient populations other than intensively pretreated HeFH patients should be selected and that the statin regimen should not be changed on study initiation.

Efficacy and safety of rosuvastatin therapy for children with familial hypercholesterolemia.

OBJECTIVES: This study was undertaken to evaluate the efficacy and safety of rosuvastatin therapy for children with familial hypercholesterolemia. BACKGROUND: Familial hypercholesterolemia is a common inherited disorder causing markedly elevated low-density lipoprotein cholesterol (LDL-C) levels from birth and resulting in premature atherosclerosis. In children, statins have been shown to be effective in reducing LDL-C, restoring flow-mediated dilation, and slowing carotid intima-media thickening. However, few children in these trials achieved current LDL-C goals. METHODS: This study comprised a 12-week double-blind, randomized, placebo-controlled trial, followed by a 40-week open-label, titration-to-goal extension phase in 177 pubertal children, ages 10 to 17 years, with familial hypercholesterolemia. Participants were randomly assigned to placebo or rosuvastatin 5, 10, or 20 mg once daily. RESULTS: Compared with placebo, rosuvastatin 5, 10, and 20 mg reduced LDL-C by 38%, 45%, and 50%, respectively (p < 0.001 for each group vs. placebo). With a maximum allowed dose of 20 mg, 40% achieved the treatment goal of <110 mg/dl during the open-label, titration-to-goal phase. Rosuvastatin was well tolerated, with no apparent adverse impact on growth or development. CONCLUSIONS: In children with familial hypercholesterolemia, rosuvastatin 20 mg daily reduced LDL-C by 50%. Nonetheless, only 40% attained the consensus LDL-C target of <110 mg/dl, reflecting these patients' high baseline LDL-C levels (mean, 232 mg/dl). (Pediatric Lipid-Reduction Trial of Rosuvastatin [PLUTO]; NCT00355615).

Limitations of statin monotherapy for the treatment of dyslipidemia: a projection based on the Canadian lipid study--observational.

OBJECTIVE: Several randomized controlled trials indicate that a low density lipoprotein cholesterol (LDL-C) target <2.0 mmol/L is appropriate for individuals at high risk of coronary artery disease (CAD). Recently released Canadian lipid management guidelines (2006) have incorporated this evidence into their recommendations. A cross-sectional study of patients treated with statins for at least 8 weeks (CALIPSO) was used as a basis to project the ability of statin monotherapy in getting high CAD-risk patients to an LDL-C level <2.0 mmol/L. RESEARCH DESIGN AND METHODS: The analysis was restricted to CALIPSO patients on statin monotherapy who were at high CAD-risk (including patients with established CAD). Assuming all patients could have their statin titrated up to the maximum dose, the proportion of patients that would reach an LDL-C level of <2.0 mmol/L was projected. To do this, the additional LDL-C reduction patients would achieve with maximal titration of their statin was estimated based on a meta-analysis of clinical trials evaluating LDL-C responses to various statin regimens, and applied to patients' current LDL-C level. RESULTS: A total of 1795 high CAD-risk patients treated with statin monotherapy were included in the analysis, of whom 69.8% had an LDL-C > or =2.0 mmol/L. Depending on the statin that was used, it was projected that between 28.2% and 62.7% of high CAD-risk patients would not attain an LDL-C of <2.0 mmol/L following statin titration to maximum dose. CONCLUSIONS: Although the accuracy of our projections may be limited by the application of clinical trials data to an external sample of patients, our results suggest that for 38% of patients at high CAD-risk, titration of statin monotherapy will not be sufficient to achieve an LDL-C target of <2.0 mmol/L. For these patients, additional treatment approaches may be needed to further reduce the risk of coronary events.

Efficacy and safety of coadministration of ezetimibe and simvastatin in adolescents with heterozygous familial hypercholesterolemia.

OBJECTIVES: The study evaluated the efficacy and safety of long-term coadministration of ezetimibe and simvastatin in adolescents with heterozygous familial hypercholesterolemia (HeFH). BACKGROUND: Aggressive intervention to achieve lipid goals for adolescents with HeFH is recommended to reduce risk of premature cardiovascular disease. METHODS: In a multicenter, randomized, double-blind, placebo-controlled study, 248 male and female subjects ages >or=10 and

Differential effect of atorvastatin and fenofibrate on plasma oxidized low-density lipoprotein, inflammation markers, and cell adhesion molecules in patients with type 2 diabetes mellitus.

Type 2 diabetes mellitus is associated with elevated plasma triglyceride levels, low high-density lipoprotein cholesterol, and a high incidence of cardiovascular disease. Hydroxymethylglutaryl-coenzyme A reductase inhibitors and fibrates are frequently used in the treatment of diabetic dyslipidemia, but their specific impact on the inflammation processes involved in atherosclerosis remains to be fully characterized. The objective of this 2-group parallel study was to investigate the differential effects of a 6-week treatment with either atorvastatin 20 mg/d alone (n = 19) or micronized fenofibrate 200 mg/d alone (n = 19) on inflammation, cell adhesion, and oxidation markers in type 2 diabetes mellitus subjects with marked hypertriglyceridemia. In addition to the expected changes in lipid levels, atorvastatin decreased plasma levels of C-reactive protein (-26.9%, P = .004), soluble intercellular adhesion molecule 1 (-5.4%, P = .03), soluble vascular cell adhesion molecule 1 (-4.4%, P = .008), sE-selectin (-5.7%, P = .02), matrix metalloproteinase 9 (-39.6%, P = .04), secretory phospholipase A(2) (sPLA(2)) (-14.8%, P = .04), and oxidized low-density lipoprotein (-38.4%, P < .0001). On the other hand, fenofibrate had no significant effect on C-reactive protein levels and was associated with reduced plasma levels of sE-selectin only (-6.0%, P = .04) and increased plasma levels of sPLA(2) (+22.5%, P = .004). These results suggest that atorvastatin was potent to reduce inflammation, oxidation, and monocyte adhesion in type 2 diabetes mellitus subjects with marked hypertriglyceridemia, whereas fenofibrate decreased sE-selectin levels only and was associated with an elevation of sPLA(2) levels.

Differential effect of fenofibrate and atorvastatin on in vivo kinetics of apolipoproteins B-100 and B-48 in subjects with type 2 diabetes mellitus with marked hypertriglyceridemia.

The specific impact of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors and fibrates on the in vivo metabolism of apolipoprotein (apo) B has not been systematically investigated in patients with type 2 diabetes mellitus with high plasma triglyceride (TG) levels. Therefore, the objective of this 2-group parallel study was to examine the differential effects of a 6-week treatment with atorvastatin or fenofibrate on in vivo kinetics of apo B-48 and B-100 in men with type 2 diabetes mellitus with marked hypertriglyceridemia. Apolipoprotein B kinetics were assessed at baseline and at the end of the intervention using a primed constant infusion of [5,5,5-D(3)]-l-leucine for 12 hours in the fed state. Fenofibrate significantly decreased plasma TG levels with no significant change in plasma low-density lipoprotein cholesterol (LDL-C) and apo B levels. On the other hand, atorvastatin significantly reduced plasma levels of TG, LDL-C, and apo B. After treatment with fenofibrate, very low-density lipoprotein (VLDL) apo B-100 pool size (PS) was decreased because of an increase in the fractional catabolic rate (FCR) of VLDL apo B-100. No significant change was observed in the kinetics of LDL apo B-100. Moreover, fenofibrate significantly decreased TG-rich lipoprotein (TRL) apo B-48 PS because of a significant increase in TRL apo B-48 FCR. After treatment with atorvastatin, VLDL and IDL apo B-100 PSs were significantly decreased because of significant elevations in the FCR of these subfractions. Low-density lipoprotein apo B-100 PS was significantly lowered because of a tendency toward decreased LDL apo B-100 production rate (PR). Finally, atorvastatin reduced TRL apo B-48 PS because of a significant decrease in the PR of this subfraction. These results indicate that fenofibrate increases TRL apo B-48 as well as VLDL apo B-100 clearance in men with type 2 diabetes mellitus with marked hypertriglyceridemia, whereas atorvastatin increases both VLDL and IDL apo B-100 clearance and decreases TRL apo B-48 and LDL apo B-100 PR.

Non-HDL cholesterol and apoB in dyslipidaemia.

On the basis of a high correlation, non-HDL-C (non-high-density lipoprotein cholesterol) and apoB (apolipoprotein B) have been suggested to be of equivalent value for clinical practice; however, the strength of this relationship has not been examined in detail in patients with dyslipidaemia. The present study examines the variance of non-HDL-C compared with apoB in 1771 consecutive patients evaluated in a lipid clinic. These patients were divided into normolipidaemic subjects (n=407), type I hyperlipoproteinaemia (n=16), type IIa (n=736) and IIb (n=231) hyperlipoproteinaemia, type III hyperlipoproteinaemia (n=38), type IV hyperlipoproteinaemia (n=509) and type V hyperlipoproteinaemia (n=101). The relationship between non-HDL-C and apoB was examined both in terms of correlation and concordance. Correlation was high, but concordance was only moderate in the normolipidaemic subjects and in those with type IIa and type IIb hyperlipoproteinaemia. Correlation and concordance were both low in the subgroups with type III and type V hyperlipoproteinaemia. In those with type IV hyperlipoproteinaemia, correlation was moderately high (r=0.74), but concordance was only fair. In conclusion, our results indicate that there is substantial variance of apoB for given values of non-HDL-C in many dyslipidaemic subjects. It follows that correlation is not adequate as a sole judge of equivalence of laboratory parameters.

Evidence of increased secretion of apolipoprotein B-48-containing lipoproteins in subjects with type 2 diabetes.

Patients with type 2 diabetes have high levels of triglyceride-rich lipoproteins (TRLs), including apolipoprotein B-48 (apoB-48)-containing TRLs of intestinal origin, but the mechanism leading to overaccumulation of these lipoproteins remains to be fully elucidated. Therefore, the objective of this study was to examine the in vivo kinetics of TRL apoB-48 and VLDL, intermediate density lipoprotein (IDL), and LDL apoB-100 in type 2 diabetic subjects (n = 11) and nondiabetic controls (n = 13) using a primed-constant infusion of l-[5,5,5-D(3)]leucine for 12 h in the fed state. Diabetic subjects had significantly higher fasting glycemia, higher fasting insulinemia, higher plasma triglyceride, and lower HDL-cholesterol levels than controls. Compared with controls, diabetic subjects had increased TRL apoB-48, VLDL apoB-100, and IDL apoB-100 pool sizes as a result of increased production rates (PRs) and reduced fractional catabolic rates of these lipoprotein subfractions. Furthermore, multiple linear regression analyses revealed that the diabetic/control status was an independent predictor of TRL apoB-48 PR and represented nearly 35% of its variance. These results suggest that the overaccumulation of TRLs seen in patients with type 2 diabetes is attributable to increased PRs of both intestinally derived apoB-48-containing lipoproteins and TRL apoB-100 of hepatic origin and to decreased catabolism of these subfractions.

Association of heterozygous familial hypercholesterolemia with smaller HDL particle size.

Small, dense HDL particles have been associated with factors known to increase the risk of cardiovascular disease, such as obesity, hypertriglyceridemia, small dense LDL particles, decreased HDL-cholesterol levels and increased apoA-I fractional catabolic rate from plasma. In order to assess the potential contribution of HDL particle size to atherosclerosis in heterozygous familial hypercholesterolemia (FH), we examined the electrophoretic characteristics of HDL particles in a large cohort of well defined FH heterozygotes and controls. A total of 259 FH heterozygotes and 208 controls participated in the study. FH subjects were carriers of one of the nine French Canadian mutations in the LDL receptor gene. All subjects were apoE3 homozygotes. HDL particles were characterized by non-denaturing polyacrylamide gradient gel electrophoresis following a 6-week lipid-lowering drug-free baseline period. The integrated HDL size was significantly smaller in the FH group compared to controls (FH=87.3+/-5.2 Angstroms versus controls=91.6+/-4.9 Angstroms, P<0.0001). In each groups, men had smaller HDL particles than women. Multiple regression linear analyses showed that the FH/Control status accounted for 20.3% of the variance in the integrated HDL size. These results suggest that the FH/control status was independently associated with variations in HDL particle size and that these variations could contribute to the development of premature atherosclerosis in these patients.

Differential impact of plasma triglycerides on HDL-cholesterol and HDL-apo A-I in a large cohort.

OBJECTIVES: To examine the relationship between plasma triglycerides (TG) to HDL-cholesterol (HDL-C) or HDL apo A-I. DESIGN AND METHODS: Bivariate and multiple linear regression analyses in a large cohort of 1886 subjects. RESULTS: Higher plasma TG levels were associated with lower concentrations of both HDL-C and HDL-apo A-I. However, the HDL-C/HDL-apo A-I ratio was inversely correlated with plasma TG indicating that the overall composition of the HDL changed as plasma TG changed. Plasma TG levels contributed to 15.9% of the variance of the HDL-C/HDL-apo A-I ratio, whereas gender, HDL-TG, LDL-TG, body mass index and plasma apo B levels represented between 0.15% and 2.21% of this variance. CONCLUSIONS: These results indicate that increasing levels of plasma TG result in greater reduction in HDL-C levels than in HDL-apo A-I and this might explain, at least in part, the differences that have been observed in the magnitude of the association of HDL-C versus HDL-apo A-I with the risk of cardiovascular disease.

Diagnosis of type III hyperlipoproteinemia from plasma total cholesterol, triglyceride, and apolipoprotein B.

OBJECTIVE: Our objective was to develop a simple algorithm that could be applied in routine clinical practice to diagnose type III hyperlipoproteinemia based on plasma total cholesterol, triglyceride and apolipoprotein (Apo) B. METHODS: Analysis of plasma lipid, lipoprotein lipid, and apolipoprotein data from 1771 patients in a tertiary care lipid clinic, from whom all data had been collected prospectively by standardized methods. Of the 1771, based on the Fredrickson classification, 16 had type I hyperlipoproteinemia, 736 type IIa hyperlipoproteinemia, 371 type IIb hyperlipoproteinemia, 38 type III hyperlipoproteinemia, 509 type IV hyperlipoproteinemia, and 101 type V hyperlipoproteinemia. RESULTS: Mean plasma ApoB was highest in type IIb (1.53 ± 0.36 g/L), borderline high (1.1 ± 0.23 g/L) in type IV, normal in type III and type V (1.04 ± 0.21 g/L and 0.96 ± 0.40 g/L, respectively) and low in type I (0.48 ± 0.16 g/L). In type III hyperlipoproteinemia, very low-density lipoprotein ApoB (ie, d<1.006 g/mL) accounted for 42.3% of total ApoB, a value that was substantially higher than in any of the other dyslipoproteinemias. The total cholesterol (TC)/ApoB ratio was similar in the uncommon dyslipoproteinemias-type I, III, and V hyperlipoproteinemia (10.5 ± 4.8, 8.7 ± 1.8, 10.3 ± 7.7, respectively)-and much higher than in the common dyslipoproteinemias-type IIa, IIb, and type IV hyperlipoproteinemia (5.0 ± 0.4, 4.6 ± 0.4, 4.9 ± 1.1, respectively). Notwithstanding that the TC/ApoB area under the curve-receiver operating characteristic (AUC-ROC) was very high (0.93), it did not discriminate among the uncommon dyslipoproteinemias. However, the triglyceride (TG)/ApoB ratio was much higher in type I (42.4 ± 28.8) and type V (25.6 ± 30.2) than in type III (5.8 ± 3.2). All cases of type III had a TC/ApoB ratio >6.2 and a TG/ApoB ratio of <10.0. Using these cutpoints, there were also no false positives. Based on the TC/ApoB ratio and the TG/ApoB ratio, the AUC-ROC was 0.99. CONCLUSIONS: These data indicate that type III hyperlipoproteinemia can be reliably diagnosed based on plasma cholesterol, TG, and ApoB.