The type of mutation in the low density lipoprotein receptor gene influences the cholesterol-lowering response of the HMG-CoA reductase inhibitor simvastatin in patients with heterozygous familial hypercholesterolaemia

Sex differences in treatment of familial hypercholesterolaemia: a meta-analysis

BACKGROUND AND AIMS

Familial hypercholesterolaemia (FH) is a highly prevalent monogenic disorder characterized by elevated LDL cholesterol (LDL-C) levels and premature atherosclerotic cardiovascular disease. Sex disparities in diagnosis, lipid-lowering therapy, and achieved lipid levels have emerged worldwide, resulting in barriers to care in FH. A systematic review was performed to investigate sex-related disparities in treatment, response, and lipid target achievement in FH (PROSPERO, CRD42022353297).

METHODS

MEDLINE, Embase, The Cochrane library, PubMed, Scopus, PsycInfo, and grey literature databases were searched from inception to 26 April 2023. Records were eligible if they described sex differences in the treatment of adults with FH.

RESULTS

Of 4432 publications reviewed, 133 met our eligibility criteria. In 16 interventional clinical trials (eight randomized and eight non-randomized; 1840 participants, 49.4% females), there were no differences between males and females in response to fixed doses of lipid-lowering therapy, suggesting that sex was not a determinant of response. Meta-analysis of 25 real-world observational studies (129 441 participants, 53.4% females) found that females were less likely to be on lipid-lowering therapy compared with males (odds ratio .74, 95% confidence interval .66-.85). Importantly, females were less likely to reach an LDL-C < 2.5 mmol/L (odds ratio .85, 95% confidence interval .74-.97). Similarly, treated LDL-C levels were higher in females. Despite this, male sex was associated with a two-fold greater relative risk of major adverse cardiovascular events including myocardial infarction, atherosclerotic cardiovascular disease, and cardiovascular mortality.

CONCLUSIONS

Females with FH were less likely to be treated intensively and to reach guideline-recommended LDL-C targets. This sex bias represents a surmountable barrier to clinical care.

Novel LDLR Variant in Familial Hypercholesterolemia: NGS-Based Identification, In Silico Characterization, and Pharmacogenetic Insights

BACKGROUND

Familial Hypercholesterolemia (FH) is a hereditary condition that causes a rise in blood cholesterol throughout a person's life. FH can result in myocardial infarction and even sudden death if not treated. FH is thought to be caused mainly by variants in the gene for the low-density lipoprotein receptor (LDLR). This study aimed to investigate the genetic variants in FH patients, verify their pathogenicity, and comprehend the relationships between genotype and phenotype. Also, review studies assessed the relationship between the LDLR null variants and the reaction to lipid-lowering therapy.

METHODS

The study utilised high-throughput next-generation sequencing for genetic screening of FH-associated genes and capillary sequencing for cascade screening. Furthermore, bioinformatic analysis was employed to describe the pathogenic effects of the revealed novel variant on the structural features of the corresponding RNA molecule.

RESULTS

We studied the clinical signs of hypercholesterolemia in a Saudi family with three generations of FH. We discovered a novel frameshift variant (c.666_670dup, p.(Asp224Alafs*43) in the LDLR and a known single nucleotide variant (c.9835A > G, p.(Ser3279Gly) in the APOB gene. It is thought that the LDLR variant causes a protein to be prematurely truncated, likely through nonsense-mediated protein decay. The LDLR variant is strongly predicted to be pathogenic in accordance with ACMG guidelines and co-segregated with the FH clinical characteristics of the family. This LDLR variant exhibited severe clinical FH phenotypes and was restricted to the LDLR protein's ligand-binding domain. According to computational functional characterization, this LDLR variant was predicted to change the free energy dynamics of the RNA molecule, thereby affecting its stability. This frameshift variant is thought to eliminate important functional domains in LDLR that are required for receptor recycling and LDL particle binding. We provide insight into how FH patients with a null variant in the LDLR gene respond to lipid-lowering therapy.

CONCLUSIONS

The findings expand the range of FH variants and assist coronary artery disease preventive efforts by improving diagnosis, understanding the genotype-phenotype relationship, prognosis, and personalised therapy for patients with FH.

Low-density lipoprotein cholesterol goal attainment in patients with clinical evidence of familial hypercholesterolemia and elevated Lp(a)

BACKGROUND

Although potent lipid-lowering therapies are available, patients commonly fall short of recommended low-density lipoprotein cholesterol (LDL-C) levels. The aim of this study was to examine the relationship between familial hypercholesterolemia (FH) and elevated lipoprotein(a) [Lp(a)] and LDL-C goal attainment, as well as the prevalence and severity of coronary artery disease (CAD). Moreover, we characterized patients failing to meet recommended LDL-C goals.

METHODS

We performed a cross-sectional analysis in a cohort of patients undergoing cardiac catheterization. Clinical FH was determined by the Dutch Clinical Lipid Network Score, and Lp(a) ≥ 50 mg/dL (≈ 107 nmol/L) was considered elevated.

RESULTS

A total of 838 participants were included. Overall, the prevalence of CAD was 72%, and 62% received lipid-lowering treatment. The prevalence of clinical FH (probable and definite FH) was 4%, and 19% had elevated Lp(a) levels. With 35%, LDL-C goal attainment was generally poor. Among the participants with clinical FH, none reached their LDL-C target. Among patients with elevated Lp(a), LDL-C target achievement was only 28%. The prevalence and severity of CAD were higher in participants with clinical FH (86% prevalence) and elevated Lp(a) (80% prevalence).

CONCLUSION

Most participants failed to meet their individual LDL-C goals according to the ESC 2016 and 2019 guidelines. In particular, high-risk patients with clinical FH or elevated Lp(a) rarely met their target for LDL-C. The identification of these patients and more intense treatment approaches are crucial for the improvement of CAD primary and secondary prevention.

Heterozygous c.1730G > C (p.Trp577Ser) variation in a case with familial hypercholesterolemia

Introduction: FH is an autosomal dominant disease of lipid metabolism. Hypercholesterolemia, xanthomas, and death from early coronary artery disease (CAD) are common in this disease due to a mutation in the LDLR, Apo-B100 or PCSK9 genes. Case report: A 4-year-old male patient with a very rare heterozygous c.1730G > C (p.Trp577Ser) variation in exon 12 of the low-density lipoprotein receptor (LDLR) gene that causes familial hypercholesterolemia (FH) was reported. As in this case, the heterozygous form may not show any symptoms in the first decade. This variation is region specific. Therefore, region-specific diagnostic criteria should be developed. Conclusion: We aimed to contribute to the literature on the development of diagnostic criteria by discussing the patient's condition with the clinical results.

Influence of the LDL-receptor genotype on statin response in heterozygous familial hypercholesterolemia: insights from the Canadian FH Registry

BACKGROUND

Whether LDL receptor (LDLR) residual activity influences the LDL-lowering effect of statins in heterozygous familial hypercholesterolemia (HeFH) remains unclear. The objective of this study was to investigate the relationship between the LDLR genotype and statin-induced LDL-C reductions in HeFH.

METHODS

A total of 615 individuals with HeFH (receptor defective (RD) genotype, n=226; receptor negative (RN) genotype, n=389) from 7 lipid clinics across Canada who initiated statin monotherapy were included in this retrospective longitudinal study. Statin-induced reductions in LDL-C among individuals with RD and RN genotypes were compared using linear models.

RESULTS

There were 334 women and 281 men with a mean untreated LDL-C concentrations of 6.97 ± 1.65 mmol/L. Untreated and on-statin LDL-C levels where higher among patients with a RN genotype [Untreated: RN: 7.24 (95% CI: 6.98, 7.50) mmol/L vs. RD: 6.70 (95% CI: 6.41, 6.98) mmol/L; P=0.0002; on-statin: RN: 4.50 (95% CI: 4.31, 4.70) vs. RD: 4.05 (95% CI: 3.84, 4.26) mmol/L; P=0.0004)]. After adjustments for age, sex, smoking status, untreated LDL-C concentrations and statin type and dose as well as the clinic where the patients were treated, the LDL-C lowering effect of statins was significantly weaker for individuals with a RN mutation compared with individuals with a RD mutation [RN: -31.1% (95% CI: (-34.7, -27.4) vs. RD: -36.5% (95% CI: -40.4, -32.6); P<0.0001]. The LDLR genotype was the strongest non-modifiable independent correlate of statin-induced LDL-C reductions (R²=2.3%; P=0.0001).

CONCLUSION

The LDLR genotype is significantly associated with statin-induced reductions in LDL-C concentrations in HeFH.

Pharmacogenomics Variability of Lipid-Lowering Therapies in Familial Hypercholesterolemia

The exponential expansion of genomic data coupled with the lack of appropriate clinical categorization of the variants is posing a major challenge to conventional medications for many common and rare diseases. To narrow this gap and achieve the goals of personalized medicine, a collaborative effort should be made to characterize the genomic variants functionally and clinically with a massive global genomic sequencing of "healthy" subjects from several ethnicities. Familial-based clustered diseases with homogenous genetic backgrounds are amongst the most beneficial tools to help address this challenge. This review will discuss the diagnosis, management, and clinical monitoring of familial hypercholesterolemia patients from a wide angle to cover both the genetic mutations underlying the phenotype, and the pharmacogenomic traits unveiled by the conventional and novel therapeutic approaches. Achieving a drug-related interactive genomic map will potentially benefit populations at risk across the globe who suffer from dyslipidemia.

Visit-to-visit variability of lipid and cardiovascular events in patients with familial hypercholesterolemia

Background

Visit-to-visit variability in lipid has been suggested as a predictor of major adverse cardiovascular events (MACEs). However, no evidence exists on the prognostic value of lipid variability in patients with familial hypercholesterolemia (FH). This prospective cohort study aimed to investigate whether lipid variability affects future MACEs in patients with FH receiving standard lipid-lowering therapy.

Methods

A total of 254 patients with FH were consecutively enrolled and followed for MACEs. Variability in the triglyceride, total cholesterol, high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) and lipoprotein (a) [Lp(a)] were evaluated from 3 months after discharge using the standard deviation (SD), coefficient of variation (CV) and variability independent of the mean (VIM).

Results

During a mean follow-up of 49 months, 22 (8.7%) events occurred. Visit-to-visit variability in Lp(a) was significantly higher in the MACE group compared to the non-MACE group. In the multivariate Cox analysis, only Lp(a)-related parameters were independent predictors for MACEs. The hazard ratios and 95% confidence intervals of each 1-SD increase of SD, CV, and VIM of Lp(a) were 1.42 (1.12-1.80), 1.50 (1.11-2.02) and 1.60 (1.16-2.22), respectively. Kaplan-Meier analysis revealed that patients with higher Lp(a) variability presented lower event-free survival. The results were consistent in various subgroups.

Conclusions

Our study firstly suggested that Lp(a) variability was associated with MACEs in real-world patients with FH, which emphasized the importance of regular lipid monitoring in the patients with high risk.

Statins for children with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia is one of the most common inherited metabolic diseases and is an autosomal dominant disorder meaning heterozygotes, or carriers, are affected. Those who are homozygous have severe disease. The average worldwide prevalence of heterozygous familial hypercholesterolemia is at least 1 in 500, although recent genetic epidemiological data from Denmark and next generation sequencing data suggest the frequency may be closer to 1 in 250. Diagnosis of familial hypercholesterolemia in children is based on elevated total cholesterol and low-density lipoprotein cholesterol levels or DNA-based analysis, or both. Coronary atherosclerosis has been detected in men with heterozygous familial hypercholesterolemia as young as 17 years old and in women with heterozygous familial hypercholesterolemia at 25 years old. Since the clinical complications of atherosclerosis occur prematurely, especially in men, lifelong treatment, started in childhood, is needed to reduce the risk of cardiovascular disease. In children with the disease, diet was the cornerstone of treatment but the addition of lipid-lowering medications has resulted in a significant improvement in treatment. Anion exchange resins, such as cholestyramine and colestipol, were found to be effective, but they are poorly tolerated. Since the 1990s studies carried out on children aged 6 to 17 years with heterozygous familial hypercholesterolemia have demonstrated significant reductions in their serum total and low-density lipoprotein cholesterol levels. While statins seem to be safe and well-tolerated in children, their long-term safety in this age group is not firmly established. This is an update of a previously published version of this Cochane Review.

OBJECTIVES

To assess the effectiveness and safety of statins in children with heterozygous familial hypercholesterolemia.

SEARCH METHODS

Relevant studies were identified from the Group's Inborn Errors and Metabolism Trials Register and Medline. Date of most recent search: 04 November 2019.

SELECTION CRITERIA

Randomized and controlled clinical studies including participants up to 18 years old, comparing a statin to placebo or to diet alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion and extracted data.

MAIN RESULTS

We found 26 potentially eligible studies, of which we included nine randomized placebo-controlled studies (1177 participants). In general, the intervention and follow-up time was short (median 24 weeks; range from six weeks to two years). Statins reduced the mean low-density lipoprotein cholesterol concentration at all time points (high-quality evidence). There may be little or no difference in liver function (serum aspartate and alanine aminotransferase, as well as creatinine kinase concentrations) between treated and placebo groups at any time point (low-quality evidence). There may be little or no difference in myopathy (as measured in change in creatinine levels) (low-quality evidence) or clinical adverse events (moderate-quality evidence) with statins compared to placebo. One study on simvastatin showed that this may slightly improve flow-mediated dilatation of the brachial artery (low-quality evidence), and on pravastatin for two years may have induced a regression in carotid intima media thickness (low-quality evidence). No studies reported rhabdomyolysis (degeneration of skeletal muscle tissue) or death due to rhabdomyolysis, quality of life or compliance to study medication.

AUTHORS' CONCLUSIONS

Statin treatment is an effective lipid-lowering therapy in children with familial hypercholesterolemia. Few or no safety issues were identified. Statin treatment seems to be safe in the short term, but long-term safety remains unknown. Children treated with statins should be carefully monitored and followed up by their pediatricians and their care transferred to an adult lipidologist once they reach 18 years of age. Large long-term randomized controlled trials are needed to establish the long-term safety issues of statins.

Spectrum of mutations of familial hypercholesterolemia in the 22 Arab countries

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is an inherited genetic disorder of lipid metabolism characterized by a high serum LDL-cholesterol profile and xanthoma formation, and FH increases the risk of premature atherosclerosis and cardiovascular disease (CVD). Mutations in the low-density lipoprotein (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin 9 (PCSK9), and LDLRAP1 genes have been associated with FH. Although FH is a major risk for CVD, the disease prevalence and its underlying molecular basis in the 22 Arab countries are still understudied. This study aimed to analyze all peer-reviewed studies related to the prevalence of FH and its causative mutations in the 22 Arab countries.

METHODS

We searched five literature databases (Scopus, Science Direct, Web of Science, PubMed, and Google Scholar) from inception until June 2018, using all possible search terms to capture all of the genetic and prevalence data related to Arab patients with FH.

RESULTS

A total of 5,484 titles and abstracts were identified; 51 studies met our inclusion criteria for the final systematic review. Fifty-one mutations in Arab patients with FH were identified in only eight Arab countries; 47 were identified in the LDLR gene, two in the PCSK9 gene, and two in LDLRAP1 gene. Twenty mutations in the LDLR gene were distinctive to Arab patients. A few studies reported prevalence estimates, ranging from 0.4% to 6.8%.

CONCLUSIONS

This is the first systematic review to dissect the up-to-date status of the genetic epidemiology of Arab patients with FH. It seems that FH is underdiagnosed and that its prevalence is understudied due to the dearth of published information about Arab patients with FH. Therefore, there is a need for well-controlled genetic epidemiological studies on Arab patients with FH.

Effect of visit-to-visit LDL-, HDL-, and non-HDL-cholesterol variability on mortality and cardiovascular outcomes after percutaneous coronary intervention

BACKGROUND AND AIMS

Visit-to-visit variability in biological measures has been suggested as an independent predictor of cardiovascular disease (CVD). Although low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) are important risk factors of CVD, there are few studies investigating the effect of variability in LDL-C and HDL-C on cardiovascular outcomes. We investigated the association between visit-to-visit variability in LDL-C, HDL-C, and non-HDL-C and major adverse cardiovascular and cerebrovascular events (MACCE) in patients who underwent percutaneous coronary intervention (PCI).

METHODS

Data from 1792 subjects who underwent PCI from January 2004 to December 2009 were analyzed. Visit-to-visit variability was calculated using various indices: standard deviation (SD), coefficient of variation, and corrected variability independent of mean (cVIM). MACCE comprised all-cause death, non-fatal myocardial infarction, and stroke.

RESULTS

During a median follow-up period of 65 months, 114 subjects (6.4%) experienced MACCE: 68 (3.8%) all-cause death; 43 (2.4%) stroke, and 15 (0.8%) non-fatal myocardial infarction. Visit-to-visit variability in LDL-C, HDL-C, and non-HDL-C was significantly higher in the MACCE group compared to the non-MACCE group. In multiple regression analysis, all LDL-C, HDL-C, and non-HDL-C variability parameters were independent predictors for MACCE after adjusting for potential confounding factors. Each 1-SD increase of cVIM in LDL-C, HDL-C, and non-HDL-C increased the risk of MACCE by 34% (HR 1.34 [95% CI, 1.18-1.52]), 50% (HR 1.50 [95% CI 1.32-1.71]), and 37% (HR 1.37 [95% CI, 1.20-1.57]), respectively. These relationships were observed in various subgroups according to age, sex, and diabetes status.

CONCLUSIONS

Visit-to-visit variability in LDL-C, HDL-C, and non-HDL-C is associated with MACCE in subjects with previous PCI.

Tendon pathology in hypercholesterolaemia patients: Epidemiology, pathogenesis and management

Tendon pathology is a general term used to describe a group of musculoskeletal conditions related to tendons and surrounding structures. There is only limited evidence available regarding the exact aetiology and natural history of tendon pathology. In hypercholesterolaemia environments, lipids could accumulate within the extracellular matrix of the tendon and thus affect the mechanical properties of the tendon. Current evidence suggested that hypercholesterolaemia was an important risk factor in the development and progression of tendon pathology. The severity of hypercholesterolaemia was correlated with the severity of tendon pathology.

The translational potential of this article: Hypercholesterolaemia lead to the structural, inflammatory and mechanical changes in tendons, which predispose hypercholesterolaemia patients to a greater risk of tendon pathology. Measurements of serum cholesterol are suggested to be performed in patients presenting with tendon pathology. The strict control of hypercholesterolaemia would mitigate the development and progression of tendon pathology.

Statins for children with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia is one of the most common inherited metabolic diseases and is an autosomal dominant disorder meaning heterozygotes, or carriers, are affected. Those who are homozygous have severe disease. The average worldwide prevalence of heterozygous familial hypercholesterolemia is at least 1 in 500, although recent genetic epidemiological data from Denmark and next generation sequencing data suggest the frequency may be closer to 1 in 250. Diagnosis of familial hypercholesterolemia in children is based on elevated total cholesterol and low-density lipoprotein cholesterol levels or DNA-based analysis, or both. Coronary atherosclerosis has been detected in men with heterozygous familial hypercholesterolemia as young as 17 years old and in women with heterozygous familial hypercholesterolemia at 25 years old. Since the clinical complications of atherosclerosis occur prematurely, especially in men, lifelong treatment, started in childhood, is needed to reduce the risk of cardiovascular disease. In children with the disease, diet was the cornerstone of treatment but the addition of lipid-lowering medications has resulted in a significant improvement in treatment. Anion exchange resins, such as cholestyramine and colestipol, were found to be effective, but they are poorly tolerated. Since the 1990s studies carried out on children aged 6 to 17 years with heterozygous familial hypercholesterolemia have demonstrated significant reductions in their serum total and low-density lipoprotein cholesterol levels. While statins seem to be safe and well-tolerated in children, their long-term safety in this age group is not firmly established. This is an update of a previously published version of this Cochane Review.

OBJECTIVES

To assess the effectiveness and safety of statins in children with heterozygous familial hypercholesterolemia.

SEARCH METHODS

Relevant studies were identified from the Group's Inborn Errors and Metabolism Trials Register and Medline.Date of most recent search: 20 February 2017.

SELECTION CRITERIA

Randomized and controlled clinical studies including participants up to 18 years old, comparing a statin to placebo or to diet alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion and extracted data.

MAIN RESULTS

We found 26 potentially eligible studies, of which we included nine randomized placebo-controlled studies (1177 participants). In general, the intervention and follow-up time was short (median 24 weeks; range from six weeks to two years). Statins reduced the mean low-density lipoprotein cholesterol concentration at all time points (moderate quality evidence). Serum aspartate and alanine aminotransferase, as well as creatinine kinase concentrations, did not differ between treated and placebo groups at any time point (low quality evidence). The risks of myopathy (low quality evidence) and clinical adverse events (moderate quality evidence) were very low and also similar in both groups. In one study simvastatin was shown to improve flow-mediated dilatation of the brachial artery (low quality evidence), and in another study treatment with pravastatin for two years induced a significant regression in carotid intima media thickness (low quality evidence).

AUTHORS' CONCLUSIONS

Statin treatment is an effective lipid-lowering therapy in children with familial hypercholesterolemia. No significant safety issues were identified. Statin treatment seems to be safe in the short term, but long-term safety remains unknown. Children treated with statins should be carefully monitored and followed up by their pediatricians and their care transferred to an adult lipidologist once they reach 18 years of age. Large long-term randomized controlled trials are needed to establish the long-term safety issues of statins.

Type of LDLR mutation and the pharmacogenetics of familial hypercholesterolemia treatment

Familial hypercholesterolemia (FH) is an autosomal dominant disease mainly caused by mutations in the low-density lipoprotein receptor (LDLR) gene. FH patients present a wide variability regarding response to drugs and they are usually undertreated. Here, we review studies that evaluated the association between the type of LDLR mutation and the response to lipid-lowering therapy. The main findings were that patients with a null LDLR mutation had: higher baseline LDL-C, higher LDL-C after drug therapy, lower proportion of patients within the LDL-C target value and higher frequencies of CVD. Thus, we conclude that FH patients harboring a null mutation have a trend to an increased risk, even if diagnosis is early established and lipid-lowering treatment instituted. It is suggested that these individuals may benefit from the use of newly approved lipid-lowering agents.

Importance of early recognition of heterozygous familial hypercholesterolaemia

PURPOSE OF REVIEW

To outline recent updates in the diagnosis and management of heterozygous familial hypercholesterolaemia.

RECENT FINDINGS

Recent guidelines have suggested that familial hypercholesterolaemia is vastly underdiagnosed in most countries worldwide. Improvements in next-generation sequencing have led to the detection of novel mutations and the cheaper cost of this technology makes the early identification of asymptomatic individuals a feasible option. With more widespread use of high doses of more potent statins in affected adults, cardiovascular mortality has decreased in adults with hypercholesterolaemia.

SUMMARY

Barriers to cascade testing of relatives of index cases remain worldwide despite improvements in gene technology and the marked recent decrease in costs of genetic testing. Recent guidelines recommending screening of young children, for example, 8-10 years with measurement of LDL cholesterol concentrations will increase the diagnosis of familial hypercholesterolaemia among children but long-term safety data of the use of statins in this young age group are not available. To date, the benefit of statin-induced decreases in LDL cholesterol concentration in children is based on effects of treatment on proxy measures of cardiovascular disease and not a reduction in cardiovascular events.

The importance of an integrated analysis of clinical, molecular, and functional data for the genetic diagnosis of familial hypercholesterolemia

PURPOSE

Familial hypercholesterolemia (FH) is one of the most common monogenic disorders, and the high concentrations of low-density lipoprotein (LDL) cholesterol presented since birth confers on these patients an increased cardiovascular risk. More than 1,600 alterations have been described in the LDL receptor gene (LDLR), but a large number need to be validated as mutations causing disease to establish a diagnosis of FH. This study aims to characterize, both at the phenotypic and genotypic levels, families with a clinical diagnosis of FH and present evidence for the importance of the integration of clinical, molecular, and functional data for the correct diagnosis of patients with FH.

METHODS

A detailed analysis of the phenotype and genotype presented by 55 families with 13 different alterations in the LDLR was conducted. For eight of these, an extensive functional characterization was performed by flow cytometry, confocal microscopy, and reverse transcriptase polymerase chain reaction.

RESULTS

Carriers of neutral alterations presented a significantly lower incidence of premature cardiovascular disease, lower levels of atherogenic lipoproteins and a large number of these individuals had LDL-cholesterol values below the 75(th) percentile. presented a significantly lower incidence of premature cardiovascular disease, lower levels of atherogenic lipoproteins and a large number of these individuals had LDL-cholesterol values below the 75th percentile However, the functional study was essential to determine the pathogenicity of variants.

CONCLUSION

The data collected illustrate the importance of this integrated analysis for the correct assessment of patients with FH who can otherwise be misdiagnosed.

Statins for children with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia is one of the most common inherited metabolic diseases; the average worldwide prevalence of heterozygous familial hypercholesterolemia is at least 1 in 500. Diagnosis of familial hypercholesterolemia in children is based on highly elevated low-density lipoprotein (LDL) cholesterol level or DNA-based analysis, or both. Coronary atherosclerosis has been detected in men with heterozygous familial hypercholesterolemia as young as 17 years old and in women with heterozygous familial hypercholesterolemia at 25 years old. Since the clinical complications of atherosclerosis occur prematurely, especially in men, lifelong hypolipidemic measures, started in childhood, are needed to reduce the risk of cardiovascular disease. In children with familial hypercholesterolemia, diet is as yet the cornerstone of treatment. Anion exchange resins, such as cholestyramine and colestipol, have also been found to be effective, but are poorly tolerated. Since the 1990s statin studies have been carried out among children with familial hypercholesterolemia (aged 7 to 17 years). Statins greatly reduced their serum LDL cholesterol levels. Even though statins seem to be safe and well-tolerated in children, their long-term safety in this age group is not firmly established.

OBJECTIVES

To assess the effectiveness and safety of statins in children with familial hypercholesterolemia.

SEARCH METHODS

Relevant studies were identified from the Group's Inborn Errors and Metabolism Trials Register and Medline.Date of most recent search: 14 October 2013.

SELECTION CRITERIA

Randomized and controlled clinical studies including participants up to 18 years old, comparing a statin to placebo or to diet alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion and extracted data.

MAIN RESULTS

We found 21 potentially eligible studies, of which we included eight randomized placebo-controlled studies (1074 participants). In general, the intervention and follow-up time was short (median 24 weeks; range from six weeks to two years). Statins reduced the mean LDL cholesterol concentration at all time points. Serum aspartate and alanine aminotransferase, as well as creatinine kinase concentrations, did not differ between treated and placebo groups at any time point. The risks of myopathy and clinical adverse events were very low and also similar in both groups. In one study simvastatin was shown to improve flow-mediated dilatation of the brachial artery, and in another study treatment with pravastatin for two years induced a significant regression in carotid intima media thickness.

AUTHORS' CONCLUSIONS

Statin treatment is an efficient lipid-lowering therapy in children with familial hypercholesterolemia. No significant safety issues were identified. Statin treatment seems to be safe in the short term, but long-term safety is unknown. Children treated with statins should be carefully monitored and followed up by their pediatricians or physicians into adulthood. Large long-term randomized controlled trials are needed to establish the long-term safety issues of statins.

Hypolipidemic treatment of heterozygous familial hypercholesterolemia: a lifelong challenge

In familial hypercholesterolemia, a defect in low-density lipoprotein receptors causes lifelong two- to threefold elevations in serum low-density lipoprotein-cholesterol levels. This leads to early atherosclerotic changes in infancy. Lifelong hypolipidemic treatment that can be started at a young age is thus greatly needed. Early diagnosis of familial hypercholesterolemia is important, and improved DNA tests for low-density lipoprotein receptor mutations have made it possible to carry out diagnosis at birth. A low saturated-fat, low cholesterol diet can be safely started at 7 months of age. This can be accompanied by dietary stanol esters from 2 years of age. At the age of 10, statin treatment can be safely started. In adults, more aggressive hypolipidemic treatment is required in order to reach the treatment goal for serum low-density lipoprotein-cholesterol levels less than 2.5 mmol/l. This can be achieved by using high doses of statin, or preferably by combining a statin with resin or ezetimibe (Zeita), Merck and Shering-Plough Pharmaceuticals). Once started, treatment of familial hypercholesterolemia is lifelong.

Presence and type of low density lipoprotein receptor (LDLR) mutation influences the lipid profile and response to lipid-lowering therapy in Brazilian patients with heterozygous familial hypercholesterolemia

OBJECTIVES

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused mainly by LDLR mutations. This study assessed the influence of the presence and type of LDLR mutation on lipid profile and the response to lipid-lowering therapy in Brazilian patients with heterozygous FH.

METHODS

For 14 ± 3 months, 156 patients with heterozygous FH receiving atorvastatin were followed. Coding sequences of the LDLR gene were bidirectionally sequenced, and the type of LDLR mutations were classified according to their probable functional class.

RESULTS

The frequencies of the types of LDLR mutations were: null-mutation (n = 40, 25.6%), defective-mutation (n = 59, 37.8%), and without an identified mutation (n = 57, 36.6%). Baseline total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were higher in patients carrying a null mutation (9.9 ± 1.9 mmol/L, 7.9 ± 1.7 mmol/L), compared to those with a defective (8.9 ± 2.2 mmol/L, 7.0 ± 2.0 mmol/L), or no mutation (7.9 ± 1.9 mmol/L, 5.8 ± 1.9 mmol/L) (p < 0.001). After treatment, the proportion of patients attaining an LDL-C<3.4 mmol/L was significantly different among groups: null (22.5%), defective (27.1%), and without mutations (47.4%) (p = 0.02). The presence of LDLR mutations was independently associated with higher odds of not achieving the LDL-C cut-off (OR 9.07, 95% CI 1.41-58.16, p = 0.02).

CONCLUSIONS

Our findings indicate that the presence and type of LDLR mutations influence lipid profile and response to lipid-lowering therapy in Brazilian patients with heterozygous FH. Thus, more intensive care with pharmacological therapeutics should be performed in patients who have a molecular analysis indicating the presence of a LDLR mutation.

A DNA microarray for the detection of point mutations and copy number variation causing familial hypercholesterolemia in Europe

To facilitate genetic cascade screening for familial hypercholesterolemia (FH) in Europe, two versions (7 and 9) of a DNA microarray were developed to detect the most frequent point mutations in the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin 9 (PCSK9) genes. The design of these microarrays is based on LIPOchip, version 4, which detects 191 LDLR and APOB mutations identified in Spanish patients with FH. A major improvement of LIPOchip, versions 7 and 9, is the ability to detect copy number variation (deletions or duplications of entire exons) in LDLR, thus abolishing the need to perform multiplex ligase-dependent probe amplification in patients with FH. The aim of this study was to validate a tool capable of detecting point mutations and copy number variations simultaneously and to evaluate its use and the newly developed software for analysis in clinical practice by reanalysis of several patients with known mutations causing FH. With the help of these validations, several aspects were analyzed, improved, and implemented in a newer version, which was evaluated through an internal validation.

How do index patients participating in genetic screening programmes for familial hypercholesterolemia (FH) interpret their DNA results? A UK-based qualitative interview study

OBJECTIVE

To explore patients' interpretations of their DNA results for familial hypercholesterolemia (FH).

METHODS

In-depth interviews were conducted with patients from two lipid clinics in Scotland, who were offered genetic testing as part of a nationwide cascade screening service.

RESULTS

Patients were receptive to taking part in genetic screening and most expected a positive result. Receiving a molecular diagnosis of FH could provide reassurance to patients that diet and lifestyle factors were not the primary causes of their condition. Patients who received inconclusive results tended to interpret this as meaning that their high cholesterol was not genetic, which could induce feelings of uncertainty and self-blame. With the exception of newly diagnosed patients, for whom a positive result could provide a useful rationale for initiating statins, most perceived DNA screening to be of little relevance to their own medication use or their own approaches to lifestyle management.

CONCLUSIONS

Index patients are likely to view DNA screening for FH as non-threatening. Receiving a positive DNA result can be reassuring for patients. Patients may not, however, interpret inconclusive DNA results correctly.

PRACTICE IMPLICATIONS

Health professionals need to ensure FH index patients are prepared to receive, and fully understand, inconclusive DNA results.

Pharmacogenetic aspects in familial hypercholesterolemia with the special focus on FHMarburg (FH p.W556R)

Objective

Familial hypercholesterolemia (FH) is an autosomal dominant inherited disorder caused by mutations in the low density lipoprotein receptor (LDLR) gene. FH is characterized by elevated plasma LDL cholesterol, premature atherosclerosis, and a high risk of premature myocardial infarction. In general, mutations within LDLR gene can cause five different classes of defects, namely: class I defect: no LDLR synthesis; class II defect: no LDLR transport; class III defect: no low density lipoprotein (LDL) to LDLR binding; class IV defect: no LDLR/LDL internalization; and class V defect: no LDLR recycling. One might expect that both the class of LDLR defect as well as the precise mutation influences the severity of hypercholesterolemia on one hand and the response on drug treatment on the other. To clarify this question we studied the effect of the LDLR mutation p.W556R in two heterozygote subjects.

Results

We found that two heterozygote FH patients with the LDLR mutation p.W556R causing a class II LDLR defect (transport defective LDLR) respond exceedingly well to the treatment with simvastatin 40 mg/ezetimibe 10 mg. There was a LDL cholesterol decrease of 55 and 64%, respectively. In contrast, two affected homozygote p.W556R FH patients, in the mean time undergoing LDL apheresis, had no response to statin but a 15% LDL cholesterol decrease on ezetimibe monotherapy.

Conclusions

The LDLR mutation p.W556R is a frequent and severe class II defect for FH. The affected homozygote FH patients have a total loss of the functional LDLR and—as expected—do not respond on statin therapy and require LDL apheresis. In contrast, heterozygote FH patients with the same LDLR defect respond exceedingly well to standard lipid-lowering therapy, illustrating that the knowledge of the primary LDLR defect enables us to foresee the expected drug effects.

Optimal management of familial hypercholesterolemia: treatment and management strategies

Familial hypercholesterolemia is an autosomally dominant disorder caused by various mutations in low-density lipoprotein receptor genes. This will lead to elevated levels of total and low-density lipoprotein cholesterol, which may in turn lead to premature coronary atherosclerosis and cardiac-related death. The symptoms are more severe in the homozygous type of the disease. Different options for the treatment of affected patients are now available. Diet therapy, pharmacologic therapy, lipid apheresis, and liver transplantation are among the various treatments. We clinically review the treatment and management strategies for the disease in order to shed light on the optimal management of familial hypercholesterolemia.

Statins for children with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia is one of the most common inherited metabolic diseases; the average worldwide prevalence of heterozygous familial hypercholesterolemia is about 1 in 500. Diagnosis of familial hypercholesterolemia in children is based on two measurements of low-density lipoprotein cholesterol level above 4.0 mmol/L or a DNA-based analysis. Coronary stenosis has been detected in men with familial hypercholesterolemia as young as 17 years old and in women with familial hypercholesterolemia at 25 years old. Atherosclerosis and its clinical complications occur prematurely, especially in men, thus lifelong hypolipidemic measures, started in childhood, are needed to reduce the risk of cardiovascular diseases. In children with familial hypercholesterolemia children, so far diet has been the main mode of treatment. Anion exchange resins, such as cholestyramine and colestipol, have also been found to be effective but are generally considered unpalatable and therefore poorly tolerated. Since the 1990s statin trials have been carried out among children with familial hypercholesterolemia (aged 7 to 17 years), and statins reduced their serum low-density lipoprotein cholesterol levels by 23% to 40%. The safety of statins among children is not well known even though statins seem to be safe and well-tolerated in adults.

OBJECTIVES

To assess the effectiveness and safety of statins in children with familial hypercholesterolemia.

SEARCH STRATEGY

Relevant trials were identified from the Group's Inborn Errors and Metabolism Trials Register and Medline.Date of most recent search: 11 March 2010.

SELECTION CRITERIA

Randomized and controlled clinical trials including participants up to 18 years old comparing a statin to placebo or to diet alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies for inclusion and extracted data.

MAIN RESULTS

We found 19 potentially eligible studies of which we included eight randomized placebo-controlled trials (897 participants). Statins reduced the mean low-density lipoprotein cholesterol concentration at all time points. There was no difference between serum aspartate and alanine aminotransferase as well as creatine kinase concentrations at any time-point. The risks of myopathy and clinical adverse events were also similar in both groups. In one study simvastatin was shown to improve flow-mediated dilation of the brachial artery.

AUTHORS' CONCLUSIONS

Statin treatment is an efficient lipid-lowering therapy in children with familial hypercholesterolemia. It seems to be safe in the short term but long-term safety is unknown. Children treated with statins should be carefully followed up by their pediatricians. Large long-term randomized controlled trials are needed to establish the long-term safety of statins.

Molecular characterization of Polish patients with familial hypercholesterolemia: novel and recurrent LDLR mutations

Autosomal dominant hypercholesterolemia (ADH) is caused by mutations in the genes coding for the low-density lipoprotein receptor (LDLR), apolipoprotein B-100 (APOB), or proprotein convertase subtilisin/kexin type 9 (PCSK9). In this study, a molecular analysis of LDLR and APOB was performed in a group of 378 unrelated ADH patients, to explore the mutation spectrum that causes hypercholesterolemia in Poland. All patients were clinically diagnosed with ADH according to a uniform protocol and internationally accepted WHO criteria. Mutational analysis included all exons, exon-intron boundaries and the promoter sequence of the LDLR, and a fragment of exon 26 of APOB. Additionally, the MLPA technique was applied to detect rearrangements within LDLR. In total, 100 sequence variations were identified in 234 (62%) patients. Within LDLR, 40 novel and 59 previously described sequence variations were detected. Of the 99 LDLR sequence variations, 71 may be pathogenic mutations. The most frequent LDLR alteration was a point mutation p.G592E detected in 38 (10%) patients, followed by duplication of exons 4-8 found in 16 individuals (4.2%). Twenty-five cases (6.6%) demonstrated the p.R3527Q mutation of APOB. Our findings imply that major rearrangements of the LDLR gene as well as 2 point mutations (p.G592E in LDLR and p.R3527Q in APOB) are frequent causes of ADH in Poland. However, the heterogeneity of LDLR mutations detected in the studied group confirms the requirement for complex molecular studies of Polish ADH patients.

Mutation detection rate and spectrum in familial hypercholesterolaemia patients in the UK pilot cascade project

Cascade testing using DNA-mutation information is now recommended in the UK for patients with familial hypercholesterolaemia (FH). We compared the detection rate and mutation spectrum in FH patients with a clinical diagnosis of definite (DFH) and possible (PFH) FH. Six hundred and thirty-five probands from six UK centres were tested for 18 low-density lipoprotein receptor gene (LDLR) mutations, APOB p.Arg3527Gln and PCSK9 p.Asp374Tyr using a commercial amplification refractory mutation system (ARMS) kit. Samples with no mutation detected were screened in all exons by single strand conformation polymorphism analysis (SSCP)/denaturing high performance liquid chromatography electrophoresis (dHPLC)/direct-sequencing, followed by multiplex ligation-dependent probe amplification (MLPA) to detect deletions and duplications in LDLR.The detection rate was significantly higher in the 190 DFH patients compared to the 394 PFH patients (56.3% and 28.4%, p > 0.00001). Fifty-one patients had inadequate information to determine PFH/DFH status, and in this group the detection rate was similar to the PFH group (25.5%, p = 0.63 vs PFH). Overall, 232 patients had detected mutations (107 different; 6.9% not previously reported). The ARMS kit detected 100 (44%) and the MLPA kit 11 (4.7%). Twenty-eight (12%) of the patients had the APOB p.Arg3527Gln and four (1.7%) had the PCSK9 p.Asp374Tyr mutation. Of the 296 relatives tested from 100 families, a mutation was identified in 56.1%. In 31 patients of Indian/Asian origin 10 mutations (two previously unreported) were identified. The utility of the ARMS kit was confirmed, but sequencing is still required in a comprehensive diagnostic service for FH. Even in subjects with a low clinical suspicion of FH, and in those of Indian origin, mutation testing has an acceptable detection rate.

Comparison of genetic versus clinical diagnosis in familial hypercholesterolemia

Early diagnosis is important in familial hypercholesterolemia (FH), a highly atherogenic condition, but internationally agreed clinical diagnostic criteria are lacking. Genetic testing for low-density lipoprotein (LDL) receptor (LDLR) and apolipoprotein B (APOB) gene defects is the preferable diagnostic method, but the best phenotype indication to proceed with genetic diagnosis has not been established. The aim of this study was to assess the predictive and accuracy values of standard diagnostic criteria for detecting disease-causing mutations in 825 subjects with clinical FH aged > or =14 years from 3 lipid clinics in Spain. All subjects underwent thorough genetic testing for the detection of LDLR and APOB defects using the Lipochip platform. FH-causing mutations were detected in 459 subjects (55.6%). By logistic regression analysis, familial or personal history of tendon xanthoma (TX) and LDL cholesterol were strongly associated with genetic diagnosis (p <0.005, R(2) = 0.41). In subjects without familial or personal histories of TX, the diagnostic criteria for FH of the Make Early Diagnosis to Prevent Early Deaths (MEDPED) project, based on age-specific LDL cholesterol thresholds, showed sensitivity of 72.4%, specificity of 71.1%, and accuracy of 71.6%. LDL cholesterol > or =190 mg/dl in subjects with familial or personal histories of TX and > or =220, > or =225, and > or =235 mg/dl in those without such histories aged <30, 30 to 39, and > or =40 years, respectively, showed sensitivity of 91.1%, specificity of 71.1%, and accuracy of 74.2% for a positive genetic diagnosis. This new set of diagnostic criteria for FH was validated in an independent group of 440 subjects from 6 additional Spanish lipid clinics. In conclusion, TX and age-adjusted LDL cholesterol cut-off values have the highest value for clinical diagnosis and indication of genetic testing in FH.

Are patients with familial hypercholesterolaemia well managed in lipid clinics? An audit of eleven clinics from the Department of Health Familial Hypercholesterolaemia Cascade Testing project

Background

Familial hypercholesterolaemia (FH) is an autosomal co-dominant disorder which is relatively common, leads to high levels of LDL-cholesterol and if untreated to early coronary heart disease. An audit of current practice at National Health Service Trusts in England was undertaken to determine whether FH patients meet the diagnostic criteria for FH; are being offered appropriate advice and treatment; and to what extent their families are contacted and offered testing for the disorder.

Methods

Medical records of known FH patients (over 18 years of age and diagnosed before 31 December 2003) were accessed to obtain information on diagnosis, treatment and family tracing.

Results

The records of 733 FH patients were examined, 79% met the UK ‘Simon Broome’ register criteria for the diagnosis of definite or possible FH. Analyses showed that patients were usually offered appropriate advice and treatment, with 89% being on a statin. However, the audit indicated a high variability in family tracing between the sites, with significant differences in the frequency of inclusion of a family pedigree in the notes (range 1–71%, mean 35%); the general practitioner (GP) being advised that first-degree relatives should be tested (range 4–52%, mean 27%); and the proportion of relatives contacted and tested (range 6–50%, mean 32%).

Conclusion

FH patients are well cared for in lipid clinics in England, are being given appropriate lifestyle advice and medication, but an increase in recording of LDL-cholesterol levels may lead to improvements in their management. Practice in family tracing appears to vary widely between clinics.

Multiplex ARMS analysis to detect 13 common mutations in familial hypercholesterolaemia

DNA analysis and mutation identification is useful for the diagnosis of familial hypercholesterolaemia (FH), particularly in the young and in other situations where clinical diagnosis may be difficult, and enables unambiguous identification of at-risk relatives. Mutation screening of the whole of the three FH-causing genes is costly and time consuming. We have tested the specificity and sensitivity of a recently developed multiplex amplification refractory mutation system assay of 11 low-density lipoprotein receptor gene (LDLR) mutations, one APOB (p.R3527Q) and one PCSK9 (p.D374Y) mutation in 400 patients attending 10 UK lipid clinics. The kit detected a mutation in 54 (14%) patients, and a complete screen of the LDLR gene using single-stranded conformation polymorphism/denaturing high performance liquid chromatography identified 59 different mutations (11 novel) in an additional 87 patients, for an overall detection rate of 35%. The kit correctly identified 38% of all detected mutations by the full screen, with no false-positive or false-negative results. In the patients with a clinical diagnosis of definite FH, the overall detection rate was higher (54/110 = 49%), with the kit detecting 52% of the full-screen mutations. Results can be obtained within a week of sample receipt, and the high detection rate and good specificity make this a useful initial DNA diagnostic test for UK patients.

The effect of apolipoprotein E polymorphism on the response to lipid-lowering treatment with atorvastatin or fenofibrate

Although the effect of apolipoprotein E gene polymorphism on the response to treatment with statins has been studied, the results are conflicting. Moreover, little is known about the possible effect of apolipoprotein E alleles on the response to treatment with fibrates. The purpose of this study was to evaluate the effect of apolipoprotein E polymorphism on lipid-lowering response to treatment with atorvastatin and fenofibrate in patients with different types of dyslipidemia. The study population included 136 patients with heterozygous familial hypercholesterolemia (type IIA dyslipidemia) treated with atorvastatin (20 mg/day) and 136 patients with either primary hypertriglyceridemia (type IV dyslipidemia) or mixed hyperlipidemia (type IIB dyslipidemia) treated with micronized fenofibrate (200 mg/day). Overall, no significant associations were detected between apolipoprotein E genotype and response to treatment with atorvastatin. In patients treated with fenofibrate, significant associations were noted between apolipoprotein E genotype and changes in apolipoprotein B, apolipoprotein E and triglyceride levels. Specifically, in apolipoprotein E2, apolipoprotein E3, and apolipoprotein E4 individuals, apolipoprotein B reductions were 22%, 17%, and 8%, respectively (P = .003); apolipoprotein E reductions were 45%, 20%, and 15%, respectively (P = .006); whereas triglyceride reductions reached 53%, 36%, and 33%, respectively (P = .033). In conclusion, apolipoprotein E genotype had no significant effect on the response to treatment with atorvastatin in patients with heterozygous familial hypercholesterolemia, but in patients with primary hypertriglyceridemia or mixed hyperlipidemia, there was a clear association between apolipoprotein E genotype and response to treatment with fenofibrate.

Pharmacogenetics: Progress, pitfalls and clinical potential for coronary heart disease

Much has been written about the potential of pharmacogenetic testing to inform therapy based on an individual's genetic makeup, and to decide the most effective choice of available drugs, or to avoid dangerous side effects. Currently, there is little hard data for either in the field of cardiovascular disease. The usual approach has been opportunistic use of drug trials in unrelated patients, and to look for differences in response or outcome by "candidate gene" genotype, for example genes coding for drug metabolising enzymes (activators and metabolisers), and enzymes and receptors involved in lipid metabolism, adrenergic response, etc. As with all association studies, initially promising results have often failed the test of replication in larger studies, and the relationship between the CETP Taq-I variant and response to statins has now been disproved. The strongest data to date is the report [Chasman, D.I., Posada, D., Subrahmanyan, L., Cook, N.R., Stanton Jr., V.P., Ridker, P.M., 2004. Pharmacogenetic study of statin therapy and cholesterol reduction. J. Am. Med. Assoc. 291, 2821-2827] of a poorer cholesterol-lowering response to Pravastatin in the 7% of patients carrying a certain haplotype of the HMG CoA reductase gene (14% fall versus 19%), but if this is overcome simply by a higher dose, it is of little clinical relevance. Currently, the best example of avoiding side effects is determining genotype at the CYP2C9 locus with respect of warfarin treatment, since carriers for functional variants (>20% of the population) require lower doses for optimal anticoagulation, and homozygotes, although rare, may well experience serious bleeding if given a usual dose. The full potential of this field will only be realised with much further work.

Mutational analysis in UK patients with a clinical diagnosis of familial hypercholesterolaemia: relationship with plasma lipid traits, heart disease risk and utility in relative tracing

As part of a randomised trial [Genetic Risk Assessment for Familial Hypercholesterolaemia (FH) Trial] of the psychological consequences of DNA-based and non-DNA-based diagnosis of FH, 338 probands with a clinical diagnosis of FH (46% with tendon xanthomas) were recruited. In the DNA-based testing arm (245 probands), using single-strand conformation polymorphism of all exons of the low-density lipoprotein receptor (LDLR) gene, 48 different pathogenic mutations were found in 62 probands (25%), while 7 (2.9%) of the patients had the R3500Q mutation in the apolipoprotein B (APOB) gene. Compared to those with no detected mutation, mean untreated cholesterol levels in those with the APOB mutation were similar, while in those with an LDLR mutation levels were significantly higher (None=9.15+/-1.62 vs LDLR=9.13+/-1.16 vs APOB=10.26+/-2.07 mmol/l p<0.001, respectively). Thirty seven percent of the detected mutations were in exon 3/4 of LDLR, and this group had significantly higher untreated cholesterol than those with other LDLR mutations (11.71+/-2.39 mmol/l vs 9.88+/-2.44 mmol/l, p=0.03), and more evidence of coronary disease compared to those with other LDLR or APOB mutations (36 vs 13% p=0.04). Of the probands with a detected mutation, 54 first-degree relatives were identified, of whom 27 (50%) had a mutation. Of these, 18 had untreated cholesterol above the 95th percentile for their age and gender, but there was overlap with levels in the non-carrier relatives such that 12% of subjects would have been incorrectly diagnosed on lipid levels alone. In the non-DNA-based testing arm (82 probands) only 19 of the 74 relatives identified had untreated cholesterol above the 95th percentile for their age and gender, which was significantly lower (p<0.0005) than the 50% expected for monogenic inheritance. These data confirm the genetic heterogeneity of LDLR mutations in the UK and the deleterious effect of mutations in exon 3 or 4 of LDLR on receptor function, lipids and severity of coronary heart disease. In patients with a clinical diagnosis of FH but no detectable mutation, there is weaker evidence for a monogenic cause compared with relatives of probands with LDLR mutations. This supports the usefulness of DNA testing to confirm diagnosis of FH for the treatment of hyperlipidaemia and for further cascade screening.

Cascade genetic screening for familial hypercholesterolemia

Familial hypercholesterolemia (FH) is caused by a mutation in the low-density lipoprotein receptor gene and is characterized by hypercholesterolemia, xanthomas, and premature coronary heart disease. Heterozygotes typically have values for total serum cholesterol in the range of 7-15 mmol/l and efficient lipid-lowering drug therapy is available. However, only approximately 20% of patients are diagnosed and less than 10% are being adequately treated. The most cost-effective strategy to diagnose patients with FH is to screen close relatives of patients already diagnosed with FH. This is referred to as cascade genetic screening. This review focuses on organization of a cascade genetic screening program for FH as well as cost-efficiency assessments, health benefits, possible adverse effects, and the screening of children. The author concludes that cascade genetic screening for FH leads to health benefits and is cost-effective without causing psychological or social damage. Accordingly, national cascade genetic screening programs for FH should be part of ordinary health care.

Genetic and environmental factors affecting the response to statin therapy in patients with molecularly defined familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is the most common inherited metabolic disease characterized by elevated serum levels of low-density lipoprotein cholesterol (LDL-C) and ischaemic heart disease early in life. Early diagnosis and treatment are essential to prevent premature atherosclerosis in FH patients. The aim of our study was the evaluation of the effects of genetic [class of the LDL receptor (LDLR) gene mutation, apolipoprotein (apo)E, apoA-IV and cholesterol ester transfer protein gene polymorphisms] and environmental factors (age, sex, smoking habit and body mass index) on the lipid-lowering response to statin therapy in patients with molecularly defined FH. Atorvastatin 20 mg/day was prescribed in 49 patients with heterozygous FH. The lipid profile was examined before and after 12 weeks of therapy. Statin therapy resulted in a decrease of 37% and 36% in LDL-C and apoB levels, respectively. The study population was then divided into 2 groups according to the class of the LDLR mutation [patients sharing a class V mutation (the G1775A mutation, n=21) and patients sharing class II mutations (the G1646A and the C858A mutations, n=28)]. In both groups, the percentage decrement in LDL-C and apoB levels were correlated with the initial LDL-C and apoB levels, respectively. The class of the LDLR mutation affected the LDL-C and apoB-lowering response of heterozygous FH patients to statin therapy. In detail, heterozygotes sharing a class V mutation of the LDLR showed a higher percentage decrement in LDL-C and apoB levels after atorvastatin administration compared to patients sharing class II mutations (49+/-9% versus 34+/-9%, P=0.001 for LDL-C and 42+/-16% versus 35+/-20%, P=0.001 for apoB). The influence of the classes of the LDLR gene mutations on the change of LDL-C and apoB levels to atorvastatin was still significant in a multivariate analysis. None of the other genetic and environmental factors studied affected the lipid-lowering response to atorvastatin therapy in patients with heterozygous FH in a multivariate analysis. Our data indicate that the class of the LDLR gene mutation affects the LDL-C and apoB-lowering response of heterozygous FH patients to statin therapy. Specifically, patients with a class V mutation exhibit higher percentage decrease in LDL-C and apoB levels after statin therapy compared to patients sharing class II mutations.

Benefits and risks assessment of simvastatin in familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is a frequent inherited monogenic disorder, associated with premature coronary artery disease. Life expectancy of FH patients is reduced by 15 - 30 years unless they are adequately treated with lipid-lowering therapy. Patients with this disorder need long-term drug therapy and the selection of treatment should be strongly based on its long-term safety and tolerability. The introduction of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors has changed the treatment of FH. Simvastatin 40 - 80 mg/day effectively reduces serum low-density lipoprotein cholesterol levels, and also reduces triglycerides with a modest rise in high-density lipoprotein cholesterol levels. Other potentially important effects, such as improvement of endothelial function, reduction of LDL oxidation and vascular inflammation, have been associated with simvastatin therapy in FH. In addition, simvastatin has been shown to abolish the progression, and even facilitate the regression of existing human atherosclerotic lesions. The safety and tolerability of simvastatin is clearly highlighted by the low rate of therapy discontinuation observed in several population-based clinical trials. Asymptomatic elevations in liver transaminase levels and myopathy are uncommon. The efficacy and tolerability of simvastatin at doses up to 80 mg/day are well-established, as well as its cost-effectiveness in the management of FH patients.

Pharmacogenetics of HMG-CoA reductase inhibitors: exploring the potential for genotype-based individualization of coronary heart disease management

Despite the benefit of statin therapy in the prevention of coronary heart disease, a considerable inter-individual variation exists in its response. It is well recognized that genetic variation can contribute to differences in drug disposition and, consequently, clinical efficacy at the population level. Pharmacogenetics, exploring genetic polymorphisms that influence response to drug therapy, may one day allow the clinician to customize treatment strategies for patients in order to improve the success rate of drug therapies. To date, 41 studies have investigated the relationships between common genetic variants and response to statin therapy in terms of lipid effects and clinical outcomes; 16 candidate genes involved in lipoprotein metabolism and 3 in pharmacokinetics. APOE is the most extensively studied locus, and absolute difference in LDL cholesterol reduction across genotypes remained 3-6%. Moreover, none of the associations was striking enough to justify genetic analysis in clinical practice. Reported data have suggested that larger studies (>1000 participants) or combination analyses with >2 different polymorphisms would enable us to find clinically or biologically meaningful difference, which could be assumed as >10% absolute difference, and that genes influencing cholesterol biosynthesis in the liver, such as ABCG5/G8, CYP7A1, HMGCR, would be good candidates for future studies.

Cardiovascular pharmacogenomics

There is large interpatient variability in the response to drugs, including cardiovascular drugs. Thus, while some patients achieve the desired therapeutic response from their drug therapy, others do not. There is also a subset of patients who will experience adverse effects, which can range from bothersome to life threatening. Research in recent years has provided compelling evidence that in many cases, genetics contributes importantly to this variable drug response. Thus, pharmacogenomics is a field focused on unravelling the genetic determinants of variable drug response. Examples from the literature of genetic associations with drug efficacy and toxicity are described to provide insight into the field, including the roles of genetic variability in drug-metabolizing enzymes and drug targets. There is also a detailed discussion of the experimental approaches used in cardiovascular pharmacogenomics. Current research is largely focused on a limited candidate gene approach, which allows for description of significant genetic associations with variable response, but often does not explain the genetic basis of variable drug response enough to be useful clinically. As such, there is a move towards genome-wide approaches, and the various technologies available to obtain genomic data are discussed. Cardiovascular pharmacogenomics has the potential for leading to improvements in the use of cardiovascular drug therapy, through selection of the most appropriate drug therapy in an individual based on their genetic information. It will probably be a decade or more before genetic information is widely used in drug therapy decisions, but it seems clear that important findings in the area will continue to expand and the experimental approaches will continue to evolve.

HMG-CoA reductase inhibitor pharmacogenomics: overview and implications for practice

HMG-CoA reductase inhibitors (statins) are widely prescribed and recommended as first-line therapy for most patients with hypercholesterolemia or established coronary heart disease. However, there is interpatient variability in lipid-lowering response to statins that is not explained by initial cholesterol levels and inadequate dosing alone. Genetic polymorphisms may contribute. This review discusses the potential contribution of polymorphisms in genes encoding proteins involved in drug metabolism and transport, cholesterol biosynthesis, lipid metabolism and others to lipid responses to statins.

Pharmacogenetics of lipid diseases

The genetic basis for most of the rare lipid monogenic disorders have been elucidated, but the challenge remains in determining the combination of genes that contribute to the genetic variability in lipid levels in the general population; this has been estimated to be in the range of 40-60 per cent of the total variability. Therefore, the effect of common polymorphisms on lipid phenotypes will be greatly modulated by gene-gene and gene-environment interactions. This approach can also be used to characterise the individuality of the response to lipid-lowering therapies, whether using drugs (pharmacogenetics) or dietary interventions (nutrigenetics). In this regard, multiple studies have already described significant interactions between candidate genes for lipid and drug metabolism that modulate therapeutic response--although the outcomes of these studies have been controversial and call for more rigorous experimental design and analytical approaches. Once solid evidence about the predictive value of genetic panels is obtained, risk and therapeutic algorithms can begin to be generated that should provide an accurate measure of genetic predisposition, as well as targeted behavioural modifications or drugs of choice and personalised dosages of these drugs.

Genetics and coronary heart disease

Genetic analysis is absolutely required to understand the architecture of complex diseases such as coronary heart disease, and such knowledge may lead to important advances in the diagnosis and treatment of the disease. On the other hand, there is presently little theoretical and empirical evidence supporting the idea that large-scale diagnostic and prognostic genetic testing for coronary heart disease might be medically useful. The situation may change however, as recent technological and population genomics advances are progressively incorporated in new appropriately designed studies.

[Analysis of lipid status parameters in relation to gender and age in the working population of district of Gradiska]

INTRODUCTION

The aim of this investigation was to establish the frequency of hyperlipoproteinemias, as well as the distribution of desired, elevated and high risk values of certain lipid status parameters among working population of the Gradiska municipality with age and sex distribution.

MATERIAL AND METHODS

This investigation included 250 workers, 109 male and 141 female, 25-60 years of age of the Gradiska municipality on a regular checkup. Standard biochemical methods were used to determine values of total serum cholesterol, triglycerides and HDL cholesterol. LDL cholesterol and LDL to HDL cholesterol ratio were calculated.

RESULTS

Total serum cholesterol was elevated in 44.04% of males and 44.68% of females, triglycerides in 20.02% of males and 19.15% of females and LDL cholesterol in 31.96% of males and 21.43% of females. High risk values of total cholesterol were established in 43.12% of males and 39.01% of females, and of triglycerides in 37.61% of males and 9.93% of females. HDL cholesterol was decreased in 55.96% of males and 41.84% of females, while highly decreased values were established only in 5.5% of males and 1.42% of females. Increase of total cholesterol and LDL cholesterol correlated with workers' age, but values of triglycerides did not. Hyperlipoproteinemia was evident in 76.4% of examinees.

DISCUSSION

All tested parameters vary dramatically from desired levels. These results are probably associated with unhealthy food habits and lifestyle.

CONCLUSION

Our results point to the need to perform regular laboratory diagnostic procedures and routine check-ups in the working population.