Roeland Huijgen

Evaluation of cholesterol lowering treatment of patients with familial hypercholesterolemia: a large cross-sectional study in The Netherlands

BACKGROUND Heterozygous familial hypercholesterolemia (heFH) is a common autosomal dominant hereditary disorder caused by mutations in the LDL-receptor gene that lead to elevated plasma levels of low-density lipoprotein-cholesterol (LDL-c). Robust lowering of LDL-c levels is essential for risk reduction of premature cardiovascular diseases and early death. European and Dutch guidelines recommend to treat LDL-c to plasma levels <2.5mmol/l. In the present study we evaluated the treatment of heFH patients in The Netherlands. METHODS A cross-sectional study was conducted in outpatient lipid clinics of three Academic Centers and two regional hospitals. Patient records of known heFH patients were retrieved and data were reviewed on the use of lipid-lowering medication, plasma lipids and lipoproteins, safety laboratory results and reasons for not achieving treatment goals. RESULTS The data of 1249 patients with heFH were available. Nearly all patients (96%) were on statin treatment. The treatment goal for LDL-c <2.5mmol/l was achieved in 261 (21%) patients. Among those who did not reach LDL-c goals, 261 (27%) were on combination therapy of maximum statin dose and ezetimibe. Main reason (32%) why patients did not use maximum therapy despite an LDL-c >or=2.5mmol/l, was acceptance of a higher target LDL-c level by the treating physician. An alternative treatment goal of >50% LDL-c reduction, as recommended in the NICE guidelines, was achieved in 47% of patients with an LDL-c >or=2.5mmol/l and not using maximum therapy. CONCLUSION Only a small proportion of patients with heFH reaches the LDL-c treatment target of <2.5mmol/l. These results emphasize the need for better monitoring, better utilization of available medication and for new treatment options in heFH to further decrease LDL-c levels.

Two Years after Molecular Diagnosis of Familial Hypercholesterolemia: Majority on Cholesterol-Lowering Treatment but a Minority Reaches Treatment Goal

Background The risk of premature cardiovascular disease in patients with familial hypercholesterolemia (FH) can be profoundly reduced by cholesterol-lowering therapy, and current guidelines for FH advocate ambitious low-density lipoprotein cholesterol (LDL-C) goals. In the present study, we determined whether these goals are reflected in current clinical practice once FH has been diagnosed. Methodology/Principal Findings In 2008, we sent questionnaires to all subjects (aged 18–65 years) who were molecularly diagnosed with FH in the year 2006 through the screening program in the Netherlands. Of these 1062 subjects, 781 completed the questionnaire (46% males; mean age: 42±12 years; mean LDL-C at molecular diagnosis (baseline): 4.1±1.3 mmol/L). The number of persons that used cholesterol-lowering therapy increased from 397 (51%) at baseline to 636 (81%) after diagnosis. Mean treated LDL-C levels decreased significantly to 3.2±1.1 mmol/L two years after diagnosis. Only 22% achieved the LDL-C target level of ≤2.5 mmol/L. Conclusions/Significance The proportion of patients using cholesterol-lowering medication was significantly increased after FH diagnosis through genetic cascade screening. The attained LDL-C levels were lower than those reported in previous surveys on medication use in FH, which could reflect the effect of more stringent lipid target levels. However, only a minority of the medication users reached the LDL-C target.

Molecular Basis of Autosomal Dominant Hypercholesterolemia Assessment in a Large Cohort of Hypercholesterolemic Children

Background— Autosomal dominant hypercholesterolemia (ADH) is characterized by elevated low-density lipoprotein cholesterol levels and premature cardiovascular disease. Mutations in the genes encoding for low-density lipoprotein receptor ( LDLR ), apolipoprotein B ( APOB ), and proprotein convertase subtilisin/kexin 9 ( PCSK9 ) underlie ADH. Nevertheless, a proportion of individuals who exhibit the ADH phenotype do not carry mutations in any of these 3 genes. Estimates of the percentage of such cases among the ADH phenotype vary widely. We therefore investigated a large pediatric population with an unequivocal ADH phenotype to assess the molecular basis of hereditary hypercholesterolemia and to define the percentage of individuals with unexplained dyslipidemia. Methods and Results— We enrolled individuals with low-density lipoprotein cholesterol levels above the 95th percentile for age and gender and an autosomal dominant inheritance pattern of hypercholesterolemia from a large referred pediatric cohort of 1430 children. We excluded children with thyroid dysfunction, nephrotic syndrome, autoimmune disease, liver disease, primary biliary cirrhosis, and obesity (body mass index >75th percentile for age and gender), as well as children referred via a cascade screening program and those from families with a known molecular diagnosis. Of the 269 children who remained after the exclusion criteria were applied, 255 (95%) carried a functional mutation ( LDLR , 95%; APOB , 5%). Conclusion— In the vast majority of children with an ADH phenotype, a causative mutation can be identified, strongly suggesting that most of the large-effect genes underlying ADH are known to date. # Clinical Perspective {#article-title-30}Background— Autosomal dominant hypercholesterolemia (ADH) is characterized by elevated low-density lipoprotein cholesterol levels and premature cardiovascular disease. Mutations in the genes encoding for low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9) underlie ADH. Nevertheless, a proportion of individuals who exhibit the ADH phenotype do not carry mutations in any of these 3 genes. Estimates of the percentage of such cases among the ADH phenotype vary widely. We therefore investigated a large pediatric population with an unequivocal ADH phenotype to assess the molecular basis of hereditary hypercholesterolemia and to define the percentage of individuals with unexplained dyslipidemia. Methods and Results— We enrolled individuals with low-density lipoprotein cholesterol levels above the 95th percentile for age and gender and an autosomal dominant inheritance pattern of hypercholesterolemia from a large referred pediatric cohort of 1430 children. We excluded children with thyroid dysfunction, nephrotic syndrome, autoimmune disease, liver disease, primary biliary cirrhosis, and obesity (body mass index >75th percentile for age and gender), as well as children referred via a cascade screening program and those from families with a known molecular diagnosis. Of the 269 children who remained after the exclusion criteria were applied, 255 (95%) carried a functional mutation (LDLR, 95%; APOB, 5%). Conclusion— In the vast majority of children with an ADH phenotype, a causative mutation can be identified, strongly suggesting that most of the large-effect genes underlying ADH are known to date.

Familial hypercholesterolemia: current treatment and advances in management

Heterozygous familial hypercholesterolemia is associated with elevated levels of LDL-cholesterol and the development of premature cardiovascular disease. The condition is considerably under-diagnosed and under-treated. Statins are the first choice treatment for all patients with heterozygous familial hypercholesterolemia. For those patients who do not reach their treatment target or who are unable to use adequate statin dose, several alternative treatment modalities can be used, either as add-on therapy or as monotherapy. In this review the various treatment options are discussed.

Advances in genetics show the need for extending screening strategies for autosomal dominant hypercholesterolaemia

Aims Autosomal dominant hypercholesterolaemia (ADH) is a major risk factor for coronary artery disease. This disorder is caused by mutations in the genes coding for the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9). However, in 41% of the cases, we cannot find mutations in these genes. In this study, new genetic approaches were used for the identification and validation of new variants that cause ADH. Methods and results Using exome sequencing, we unexpectedly identified a novel APOB mutation, p.R3059C, in a small-sized ADH family. Since this mutation was located outside the regularly screened APOB region, we extended our routine sequencing strategy and identified another novel APOB mutation (p.K3394N) in a second family. In vitro analyses show that both mutations attenuate binding to the LDLR significantly. Despite this, both mutations were not always associated with ADH in both families, which prompted us to validate causality through using a novel genetic approach. Conclusion This study shows that advances in genetics help increasing our understanding of the causes of ADH. We identified two novel functional APOB mutations located outside the routinely analysed APOB region, suggesting that screening for mutations causing ADH should encompass the entire APOB coding sequence involved in LDL binding to help identifying and treating patients at increased cardiovascular risk.

Colesevelam added to combination therapy with a statin and ezetimibe in patients with familial hypercholesterolemia: a 12-week, multicenter, randomized, double-blind, controlled trial.

BACKGROUND Familial hypercholesterolemia (FH) has been associated with increased cardiovascular risk when untreated or when normal LDL-C concentrations are not reached. Some patients with FH do not reach LDL-C goals despite intensive combination therapy. OBJECTIVE This study assessed the efficacy and tolerability of colesevelam added to maximally tolerated, stable-dose combination treatment with a statin + ezetimibe. METHODS This Phase IV, multicenter, randomized, double-blind, placebo-controlled trial enrolled patients aged 18 to 75 years with FH and an LDL-C concentration >2.5 mmol/L who were receiving a maximally tolerated and stable regimen of a statin + ezetimibe. Patients were randomly assigned to receive colesevelam 3.75 g/d or placebo added to the statin + ezetimibe for 12 weeks. The primary efficacy outcome was the difference in LDL-C between the colesevelam and placebo groups after 6 weeks. Secondary efficacy outcomes were between-group differences in LDL-C, total cholesterol (TC), HDL-C, triglyceride (Tg), apolipoprotein (apo) B, and apoA-I concentrations, as well as apoB/apoA-I ratio after 12 weeks. Tolerability was assessed based on the prevalences of adverse events by organ system class in each treatment group. RESULTS Eighty-six patients were randomized (45 colesevelam, 41 placebo), of whom 84 (44 colesevelam, 40 placebo) were included in the primary analysis. The mean (SD) age of the participants was 52.8 (10.8) years, and 51 (59%) were men. The difference (95% CI) in LDL-C between colesevelam and placebo after 6 weeks was -18.5% (-25.3 to -11.8). Between-group differences in LDL-C, TC, HDL-C, Tg, and apoB/apoA-I ratio after 12 weeks were -12.0% (-17.8 to -6.3), -7.3% (-12.0 to -2.6), +3.3% (-2.4 to +9.0), +2.8% (-10.4 to +15.9), and -12.2% (-20.2 to -4.2), respectively. Colesevelam was generally well tolerated, with gastrointestinal adverse events in 12 of 45 patients (27%) versus 7 of 40 (18%) in the placebo group (P = NS). CONCLUSION In these patients with FH, colesevelam added to a combination of a statin + ezetimibe was associated with significantly improved LDL-C concentrations compared with placebo during the 12-week study period and was generally well tolerated.

RETRACTED: Plasma PCSK9 Levels and Clinical Outcomes in the TNT (Treating to New Targets) Trial: A Nested Case-Control Study

OBJECTIVES The purpose of this study was to investigate whether high levels of circulating proprotein convertase subtilisin kexin type 9 (PCSK9) would increase cardiovascular risk in statin-treated patients. BACKGROUND Statins activate low-density lipoprotein (LDL) receptor gene expression, thus lowering plasma LDL levels. But statins also activate the expression of PCSK9, a secreted inhibitor of the LDL receptor, thereby limiting their beneficial effects. METHODS We have measured the plasma PCSK9 levels of 1,613 patients with stable coronary heart disease enrolled in the Treating to New Targets study, a randomized trial that compared the efficacy of high- versus low-dose atorvastatin. After a run-in period with atorvastatin 10 mg daily, patients were randomized to either continue with 10 mg or be up-titrated to 80 mg of atorvastatin, and followed during 5 years for major cardiovascular events (MCVEs). RESULTS Circulating PCSK9 levels measured at randomization were predictive of clinical outcomes in the group randomized to remain on atorvastatin 10 mg (p = 0.039), but not in the group that intensified atorvastatin treatment to 80 mg (p = 0.24). Further, PCSK9 levels measured 1 year post-randomization did not change upon increase of the statin dose. CONCLUSIONS PCSK9 levels predict cardiovascular events in patients treated with low-dose atorvastatin. (A Study to Determine the Degree of Additional Reduction in CV Risk in Lowering LDL Below Minimum Target Levels [TNT]; NCT00327691).

Cardiovascular risk in relation to functionality of sequence variants in the gene coding for the low-density lipoprotein receptor: a study among 29 365 individuals tested for 64 specific low-density lipoprotein-receptor sequence variants

AIMS A plethora of mutations in the LDL-receptor gene (LDLR) underlie the clinical phenotype of familial hypercholesterolaemia (FH). For the diagnosis of FH, it is important, however, to discriminate between pathogenic and non-pathogenic mutations. The aim of the current study was to assess whether true pathogenic mutations were indeed associated with the occurrence of coronary artery disease (CAD) when compared with non-functional variants. The latter variants should not exhibit such an association with CAD. METHODS AND RESULTS We assessed 29 365 individuals tested the 64 most prevalent LDLR variants. First, we determined pathogenicity for each of these sequence variants. Subsequently, a Cox-proportional hazard model was used to compare event-free survival, defined as the period from birth until the first CAD event, between carriers and non-carriers of LDLR mutations. Fifty-four sequence variants in the LDLR gene were labelled as pathogenic and 10 as non-pathogenic. The 9 912 carriers of a pathogenic LDLR mutation had a shorter event-free survival than the 18 393 relatives who did not carry that mutation; hazard ratio 3.64 [95% confidence interval (CI): 3.24-4.08; P< 0.001]. In contrast, the 355 carriers of a non-pathogenic LDLR variant had similar event-free survival as the 705 non-carrying relatives; hazard ratio 1.00 (95% CI: 0.52-1.94; P= 0.999). CONCLUSION These findings with respect to clinical outcomes substantiate our criteria for functionality of LDLR sequence variants. They also confirm the CAD risk associated with FH and underline that these criteria can be used to decide whether a specific sequence variant should be used in cascade screening.

Factor VIII deficiency does not protect against atherosclerosis

See also Makris M, van Veen JJ. Reduced cardiovascular mortality in hemophilia despite normal atherosclerotic load. This issue, pp 20–2; Zwiers M, Lefrandt JD, Mulder DJ, Smit AJ, Gans ROB, Vliegenthart R, Brands‐Nijenhuis AVM, Kluin‐Nelemans JC, Meijer K. Coronary artery calcification score and carotid intima–media thickness in patients with hemophilia. This issue, pp 23–9.

Plasma levels of PCSK9 and phenotypic variability in familial hypercholesterolemia.

The extent of hypercholesterolemia varies considerably in patients with familial hypercholesterolemia (FH). We hypothesized that the variability of the FH phenotype might be partly explained by variation in proprotein convertase subtilisin kexin type 9 (PCSK9) activity. Individuals between 18 and 53 years of age who had been tested for a pathogenic LDLR or APOB mutation were eligible. Mutation carriers with a LDL-C level below the 75th percentile (called “FH low”) were selected, as well as those with LDL-C above the 90th percentile (called “FH high”). Relatives who tested negative for the mutation were the “controls.” PCSK9 plasma levels were assessed in 267 individuals who did not receive cholesterol-lowering treatment at the time of the study. Mean PCSK9 plasma levels (95% CI) were lower in the FH-low group compared with the FH-high group [152 (137–167) ng/ml vs. 186 (165–207) ng/ml, P = 0.010] and the control group [177 (164–190) ng/ml, P = 0.013]. Mean PCSK9 levels did not statistically differ between the FH-high and control groups (P = 0.50). Plasma PCSK9 levels are positively associated with LDL-C levels in FH patients and might contribute to the phenotypic severity in this disorder. Therefore, the results of pharmaceutical inhibition of PCSK9 in FH patients are eagerly awaited.