Lipid-lowering response of the HMG-CoA reductase inhibitor fluvastatin is influenced by polymorphisms in the low-density lipoprotein receptor gene in Brazilian patients with primary hypercholesterolemia

Pharmacogenomics of statins: lipid response and other outcomes in Brazilian cohorts

Statins are inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in cholesterol biosynthesis, that are highly effective in reducing plasma low-density lipoprotein (LDL) cholesterol and decreasing the risk of cardiovascular events. In recent years, a multitude of variants in genes involved in pharmacokinetics (PK) and pharmacodynamics (PD) have been suggested to influence the cholesterol-lowering response. However, the vast majority of studies have analyzed the pharmacogenetic associations in populations in Europe and the USA, whereas data in other populations, including Brazil, are mostly lacking. This narrative review provides an update of clinical studies on statin pharmacogenomics in Brazilian cohorts exploring lipid-lowering response, adverse events and pleiotropic effects. We find that variants in drug transporter genes (SLCO1B1 and ABCB1) positively impacted atorvastatin and simvastatin response, whereas variants in genes of drug metabolizing enzymes (CYP3A5) decreased response. Furthermore, multiple associations of variants in PD genes (HMGCR, LDLR and APOB) with statin response were identified. Few studies have explored statin-related adverse events, and only ABCB1 but not SLCO1B1 variants were robustly associated with increased risk in Brazil. Statin-related pleiotropic effects were shown to be influenced by variants in PD (LDLR, NR1H2) and antioxidant enzyme (NOS3, SOD2, MTHFR, SELENOP) genes. The findings of these studies indicate that statin pharmacogenomic associations are distinctly different in Brazil compared to other populations. This review also discusses the clinical implications of pharmacogenetic studies and the rising importance of investigating rare variants to explore their association with statin response.

Characterization of LDLR rs5925 and PCSK9 rs505151 genetic variants frequencies in healthy subjects from northern Chile: Influence on plasma lipid levels

Background

Identification and characterization of genetic variants and their effects on human health may allow to establish relationships between genetic background and susceptibility to developing cardiovascular diseases. LDLR and PCSK9 polymorphisms have been associated with higher lipid levels and risk of cardiovascular diseases. Thus, the main aim of this study was to evaluate genotype distribution and relative allelic frequency of LDLR rs5925 (1959C > T) and PCSK9 rs505151 (23968 A > G) genetic variants and their effects on lipid levels of healthy subjects from northern Chile.

Methods

A total of 178 healthy individuals were recruited for this study. The genotyping of rs5925 (LDLR) and rs505151 (PCSK9) polymorphisms was performed by PCR‐RFLP and qPCR, respectively. In addition, glucose and lipid levels were determined and associated with the genetic data.

Results

Genotype distribution for LDLR rs5925 polymorphism was as follows: CC = 19%; CT = 53%; and TT = 28% (HWE: χ² = 0.80; P = .37), and for PCSK9 rs505151 genetic variant was as follows: AA = 93%; AG = 7%; and GG = 0% (HWE: χ² = 0.22; P = .64). The frequency of T (rs5925) and G (rs505151) mutated alleles was 0.55 and 0.03, respectively. Data showed that individuals carrying LDLR mutated allele (T) presented lower values of total cholesterol, triglycerides, and LDL‐cholesterol when compared to CC homozygous genotype (P < .05). Subgroup analysis revealed that women carrying the PCSK9 mutated allele (G) exhibited higher values of total cholesterol, triglycerides, HDL‐C, and LDL‐C when compared to male group carrying the same genotype (P < .05).

Conclusions

The effect of LDLR rs5925 and PCSK9 rs505151 gene polymorphisms on lipid levels is associated with gender among healthy subjects from northern Chile.

Seventeen years of statin pharmacogenetics: a systematic review

AIM

We evaluated the evidence of pharmacogenetic associations with statins in a systematic review.

METHODS

Two separate outcomes were considered of interest: modification of low-density lipoprotein cholesterol (LDL-C) response and modification of risk for cardiovascular events.

RESULTS

In candidate gene studies, 141 loci were claimed to be associated with LDL-C response. Only 5% of these associations were positively replicated. In addition, six genome-wide association studies of LDL-C response identified common SNPs in APOE, LPA, SLCO1B1, SORT1 and ABCG2 at genome-wide significance. None of the investigated SNPs consistently affected the risk reduction for cardiovascular events.

CONCLUSION

Only five genetic loci were consistently associated with LDL-C response. However, as effect sizes are modest, there is no evidence for the value of genetic testing in clinical practice.

APOE polymorphisms contribute to reduced atorvastatin response in Chilean Amerindian subjects

Genetic factors can determine the high variability observed in response to lipid-lowering therapy with statins. Nonetheless, the frequency of single nucleotide polymorphisms (SNPs) and their impact can vary due to ethnicity. Because the Chilean population carries a strong Amerindian background, the objective of this study was to evaluate the influence of apolipoprotein E (APOE) variants (rs429358, rs7412) and the 1959C>T SNP (rs5925) in the low-density lipoprotein receptor (LDLR) in response to atorvastatin treatment in hypercholesterolemic individuals. A hundred and thirty nine subjects undergoing statin therapy were included. Identification of Amerindian mtDNA haplogroups was determined by polymerase chain reaction (PCR) and PCR followed by restriction fragment length polymorphism (RFLP), respectively. SNPs were determined by PCR-RFLP. Out of the 139 individuals studied, 84.4% had an Amerindian background, according to mtDNA analysis. In relation to APOE variants, carriers of the E3/4 genotype presented lower cholesterol reduction compared to genotype E3/3 (LDL-C: -18% vs. -29%, p ˂ 0.001). On the other hand, the LDLR rs5925 SNP was not related to atorvastatin response (p = 0.5760). Our results suggest that APOE SNPs are potential predictors to atorvastatin therapy in Amerindian Chilean subjects.

Association between Pro12Ala, Pvull, Avall, Sstl and ADIPOQ single-nucleotide polymorphisms with lipid and glycemic profiles of patients with Berardinelli-Seip syndrome

BACKGROUND/AIMS

Berardinelli-Seip syndrome (BSS) is a recessive autosomal genetic disorder characterized by the near loss of adipose tissue with disturbance in lipid metabolism.

METHODS

Biochemical and hormonal parameters and Pro12Ala, Pvull, Avall, Sstl and ADIPOQ polymorphisms in 22 patients with BSS were analyzed and examined for a possible association with lipid profiles.

RESULTS

Parental consanguinity, insulin resistance and diabetes mellitus were observed in 63.6, 81.8 and 59.1% of patients, respectively. All individuals presented high triglyceride levels, and 68.1% of patients showed high cholesterol levels. The Pro/Pro genotype of the Pro12Ala polymorphism of the PPARγ2 gene was found in 86.3% of patients; the Ala/Ala variant was not observed in any patient. The PvuII polymorphism of the LPL gene showed a frequency of 50% for the P1P2 variant. The AvaII polymorphism of the LDLR gene showed a similar frequency of 40.9% for both CT and TT variants. The S1S1 genotype of the Sstl polymorphism of the APOC3 gene had a frequency of 86.3%. The CC allele of the ADIPOQ polymorphism of the adiponectin gene was found in 54.6% of patients.

CONCLUSIONS

No association was found between lipid parameters and the relevant Pvull, Avall and Sstl polymorphisms. However, we did observe an association of the Pro12Ala and ADIPOQ polymorphisms with higher lipid levels, suggesting a close relationship between these factors.

Resistance and intolerance to statins

BACKGROUND AND AIMS

Many patients treated with statins are considered statin-resistant because they fail to achieve adequate reduction of low density lipoprotein cholesterol (LDL-C) levels. Some patients are statin-intolerant because they are unable to tolerate statin therapy at all or to tolerate a full therapeutic statin dose because of adverse effects, particularly myopathy and increased activity of liver enzymes.

RESULTS

The resistance to statins has been associated with polymorphisms in the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA-R), P-glycoprotein (Pg-P/ABCB1), breast cancer resistance protein (BCRP/ABCG2), multidrug resistance-associated proteins (MRP1/ABCC1 and MRP2/ABCC2), organic anion transporting polypeptides (OATP), RHOA, Nieman-Pick C1-like1 protein (NPC1L1), farnesoid X receptor (FXR), cholesterol 7alpha-hydroxylase (CYP7A1), Apolipoprotein E (ApoE), proprotein convertase subtilisin/kexin type 9 (PCSK9), low density lipoprotein receptor (LDLR), lipoprotein (a) (LPA), cholesteryl ester transfer protein (CETP), and tumor necrosis factor α (TNF-α) genes. However, currently, there is still not enough evidence to advocate pharmacogenetic testing before initiating statin therapy. Patients with inflammatory states and HIV infection also have diminished LDL-C lowering as a response to statin treatment. Pseudo-resistance due to nonadherence or non-persistence in real-life circumstances is probably the main cause of insufficient LDL-C response to statin treatment.

CONCLUSIONS

If a patient is really statin-resistant or statin-intolerant, several other treatment possibilities are nowadays available: ezetimibe alone or in combination with bile acid sequestrants, and possibly in the near future mipomersen, lomitapide, or monoclonal antibodies against PCSK9.

Statin myotoxicity: a review of genetic susceptibility factors

The 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase inhibitors (statins) are among the most common medications prescribed worldwide, but their efficacy and toxicity vary between individuals. One of the major factors contributing to intolerance and non-compliance are the muscle side-effects, which range from mild myalgia through to severe life-threatening rhabdomyolysis. One way to address this is pharmacogenomic screening, which aims to individualize therapy to maximize efficacy whilst avoiding toxicity. Genes encoding proteins involved in the metabolism of statins as well as genes known to cause inherited muscle disorders have been investigated. To-date only polymorphisms in the SLCO1B1 gene, which encodes the protein responsible for hepatic uptake of statins, and the COQ2 gene, important in the synthesis of coenzyme Q10, have been validated as being strongly associated with statin-induced myopathy. The aim of this review is to summarize studies investigating genetic factors predisposing to statin myopathy and myalgia, as the first step towards pharmacogenomic screening to identify at risk individuals.

Pharmacogenetics in cardiovascular disease: the challenge of moving from promise to realization: concepts discussed at the Canadian Network and Centre for Trials Internationally Network Conference (CANNeCTIN), June 2009

Pharmacogenetics in cardiovascular medicine brings the potential for personalized therapeutic strategies that improve efficacy and reduce harm. Studies evaluating the impact of genetic variation on pharmacologic effects have been undertaken for most major cardiovascular drugs, including antithrombotic agents, β-adrenergic receptor blockers, statins, and angiotensin-converting enzyme inhibitors. Across these drug classes, many polymorphisms associated with pharmacodynamic, pharmacokinetic, or surrogate outcomes have been identified. However, their impact on clinical outcomes and their ability to improve clinical practice remains unclear. This review will examine the current clinical evidence supporting pharmacogenetic testing in cardiovascular medicine, provide clinical guidance based on the current evidence, and identify further steps needed to determine the utility of pharmacogenetics in cardiovascular care.

[Analysis of the mRNA expression of the S100β protein in adipocytes of patients with diabetes mellitus, type 2]

OBJECTIVE

This study aims to explore the possible relationship between the expression level of S100β protein mRNA with diabetes mellitus type 2 in adipocytes from patients with this disease in comparison with normoglycemic individuals.

MATERIALS AND METHODS

Samples of adipose tissue of eight patients from the coronary section of the Institute Dante Pazzanese of Cardiology (IDPC), four in Group Diabetes and four of Normoglycemic group, were evaluated by RT-PCR real time.

RESULTS

An increase around 15 times values, between the threshold cycle (ΔCt), of mRNA expression of S100β protein in adipocytes of the diabetes group was observed in comparison to the control group (p = 0.015).

CONCLUSION

Our results indicate, for the first time, that there is coexistence of increased expression of the S100β and the type 2 diabetes mellitus gene.

Statin dose in Asians: is pharmacogenetics relevant?

Historically the efficacy and safety of statins has mostly been studied in western populations. Few such studies have been carried out in Asians until recent years. These studies revealed interesting similarities and differences for statin use between Asians and Caucasians. One clinically important question subsequently raised is whether Asians need lower statin doses compared with Caucasians. Many practicing physicians believe that statin doses are lower in Asians because of the generally lower bodyweight and BMI. Whether this belief is based on sound scientific evidence needs to be reviewed. Furthermore, since the decision of optimal dose is based on both efficacy and safety, both of which may be impacted by genetic factors, one may ask whether pharmacogenetics plays a role in the dose difference, if such a difference exists. There is a clinical need to critically and comprehensively article the literature to answer these questions, and summarize future directions of research in the field. This article serves the above purpose.

Identification of pharmacogenetic predictors of lipid-lowering response to atorvastatin in Chilean subjects with hypercholesterolemia

BACKGROUND

Statins are normally the first-line therapy for hypercholesterolemia (HC); however, the lipid-lowering response shows high interindividual variation. We investigated the effect of four polymorphisms in CYP3A4, CYP3A5 and ABCB1 genes on response to atorvastatin and CYP3A4 activity in Chilean subjects with HC.

METHODS

A total of 142 hypercholesterolemic individuals underwent atorvastatin therapy (10mg/day/1month). Serum lipid levels before and after treatment were measured. Genetic variants in CYP3A4 (-290A>G, rs2740574), CYP3A5 (6986A>G, rs776746) and ABCB1 (2677G>A/T, rs2032582 and 3435C>T, rs1045642) were analyzed by PCR-RFLP. CYP3A4 enzyme activity in urine samples was assessed through determination of 6β-hydroxycortisol/cortisol free ratio (6βOHC/FC).

RESULTS

After 4weeks of therapy, a significant reduction in total cholesterol (TC) and LDL-c was observed (P<0.001). The G allele for -290A>G polymorphism was related to higher percentage of variation in TC and LDL-c (P<0.001). Moreover, same allele was associated with higher HDL-c variation (P=0.017). In addition, CYP3A4 enzyme activity was lower in subjects carrying this polymorphism (P=0.009). No differences were observed for CYP3A5 and ABCB1 variants.

CONCLUSION

Our results suggest that presence of G allele for -290A>G polymorphism determines a better response to atorvastatin, being also associated with lower CYP3A4 activity in vivo, causing an increased atorvastatin activity.

Common sequence variants in pharmacodynamic and pharmacokinetic pathway-related genes conferring LDL cholesterol response to statins

AIMS

This study assessed the association between pharmacokinetic- and pharmacodynamic-related genes and individual responses to low-density lipoprotein cholesterol (LDL-C) change by statins in a Chinese population.

MATERIALS & METHODS

A total of 386 patients with primary hypercholesterolemia were treated with statins for 9 months. The 62 haplotype-tagging SNPs of ten candidate genes were genotyped. Treating LDL-C reduction as an outcome variable, we performed multiple linear regression models in various modes of inheritance to test the effects of SNP and haplotype variants.

RESULTS

After correction for the multiple tests, only rs12916 in HMGCR and rs9902941 in SREBF1 remained significant. For rs12916 in the HMGCR gene, individuals with CC genotype showed a reduction of 56.9 mg/dl for LDL-C, with the reduction increasing to 60.1 and 62.5 mg/dl among individuals carrying CT and TT, respectively (p-value for additive model = 0.006). For the HMGCR gene, subjects carrying the CCGTCCA haplotype had a significant increase of LDL-C (adjusted mean -7.2 +/- 2.3 mg/dl; p-value for global test = 0.002). For the ABCG8 gene, subjects carrying the ATTATCGAC haplotype had a significant reduction of LDL-C (adjusted mean -13.0 +/- 4.6 mg/dl; p-value for global test = 0.005).

CONCLUSION

Our results indicated a strong association of sequence variants of HMGCR, SREBF1 and ABCG8 genes with the reduction of LDL-C after statin treatment in a Chinese population. Future studies on the genes of drug-metabolism enzymes and transporters are warranted.

Genetic determinants of response to statins

In developed countries, cardiovascular disease is one of the leading causes of death. Statins are abundantly prescribed to reduce the risk of coronary artery disease by lowering cholesterol. Genetic factors are thought to be partly responsible for the interindividual variation in the response to statins. This article reviews the most important studies conducted on pharmacogenetics of statins. Currently, there is no evidence to advocate pharmacogenetic testing before initiating therapy.

Atorvastatin effects on SREBF1a and SCAP gene expression in mononuclear cells and its relation with lowering-lipids response

BACKGROUND

The transcription factors SREBP1 and SCAP are involved in intracellular cholesterol homeostasis. Polymorphisms of these genes have been associated with variations on serum lipid levels and response to statins that are potent cholesterol-lowering drugs. We evaluated the effects of atorvastatin on SREBF1a and SCAP mRNA expression in peripheral blood mononuclear cells (PBMC) and a possible association with gene polymorphisms and lowering-cholesterol response.

METHODS

Fifty-nine hypercholesterolemic patients were treated with atorvastatin (10 mg/day for 4 weeks). Serum lipid profile and mRNA expression in PBMC were assessed before and after the treatment. Gene expression was quantified by real-time PCR using GAPD as endogenous reference and mRNA expression in HepG2 cells as calibrator. SREBF1 -36delG and SCAP A2386G polymorphisms were detected by PCR-RFLP.

RESULTS

Our results showed that transcription of SREBF1a and SCAP was coordinately regulated by atorvastatin (r=0.595, p<0.001), and that reduction in SCAP transcription was associated with the 2386AA genotype (p=0.019). Individuals who responded to atorvastatin with a downregulation of SCAP had also a lower triglyceride compared to those who responded to atorvastatin with an upregulation of SCAP.

CONCLUSION

Atorvastatin has differential effects on SREBF1a and SCAP mRNA expression in PBMC that are associated with baseline transcription levels, triglycerides response to atorvastatin and SCAP A2386G polymorphism.

Statin pharmacogenomics: what have we learned, and what remains unanswered?

PURPOSE OF REVIEW

Statins are widely prescribed and are established as first-line therapy for the primary and secondary prevention of coronary heart disease. Response to treatment varies considerably from person to person; however, inherited traits (genetic variability) may play a central role in this inter-individual variation. The purpose of this review is to summarize recent progress in the research for exploring genetic determinants of clinical efficacy and safety of statin therapy.

RECENT FINDINGS

In addition to 41 previous studies of 19 genes, the results of 17 pharmacogenomic studies investigating the relationship between common genetic variants and response to statin therapy in terms of lipid responses, clinical outcomes, and adverse events have been reported since January 2004 - 15 candidate genes related to pharmacodynamics and three to pharmacokinetics of statins. These reported data suggest that genetic variations influencing intestinal cholesterol absorption, cholesterol production, and lipoprotein catabolism may all play a role in modulating responsiveness, as well as genes involved in drug metabolism of statins. They also suggest that combined analysis of multiple variants in several genes, all of which have possible functional relations, is more likely to give significant results, especially when being performed with a larger number of participants.

SUMMARY

Pharmacogenomic studies of statin therapy will provide a better picture as to who is most likely and least likely to benefit from treatment, which results in more individualized management of coronary artery disease.

Pharmacogenomics of statin responsiveness

Statins are widely prescribed and are established as first-line therapy for the primary and secondary prevention of coronary artery disease. However, the benefit of treatment varies between patients. Genetic variation can contribute to interindividual variations in clinical efficacy of drug therapy, and significant progress has been made in identifying common genetic polymorphisms that influence responsiveness to statin therapy. To date, >30 candidate genes related to pharmacokinetics and pharmacodynamics of statins have been investigated as potential determinants of drug responsiveness in terms of low-density lipoprotein cholesterol lowering. Genetic variation at gene loci that affect intestinal cholesterol absorption include apolipoprotein (apo) E; adenosine triphosphate-binding cassette transporter G5 and G8; cholesterol production, such as 3-hydroxy-3-methylglutaryl coenzyme A reductase; and lipoprotein catabolism, such as apoB and the low-density lipoprotein receptor, all may play a role in modulating responsivesness as well genes involved in metabolism of statins such as cytochrome P450. However, there is considerable variation in results reported, and the data suggest that combined analysis of multiple genetic variants in several genes, all of which have possible functional significance, is more likely to give significant results than single gene studies in small sample populations. In the future, pharmacogenomic studies with a greater number of participants (>2,000 participants) should provide a better picture as to who is most likely and who is least likely to benefit from statin therapy.

An association study of 43 SNPs in 16 candidate genes with atorvastatin response

Variation in individual response to statin therapy has been widely studied for a potential genetic component. Multiple genes have been identified as potential modulators of statin response, but few study findings have replicated. To further examine these associations, 2735 individuals on statin therapy, half on atorvastatin and the other half divided among fluvastatin, lovastatin, pravastatin and simvastatin were genotyped for 43 SNPs in 16 genes that have been implicated in statin response. Associations with low-density lipoprotein cholesterol (LDL-C) lowering, total cholesterol lowering, HDL-C elevation and triglyceride lowering were examined. The only significant associations with LDL-C lowering were found with apoE2 in which carriers of the rare allele who took atorvastatin lowered their LDL-C by 3.5% more than those homozygous for the common allele and with rs2032582 (S893A in ABCB1) in which the two groups of homozygotes differed by 3% in LDL-C lowering. These genetic effects were smaller than those observed with the demographic variables of age and gender. The magnitude of all the differences found is sufficiently small that genetic data from these genes should not influence clinical decisions on statin administration.

Baseline levels of low-density lipoprotein cholesterol and lipoprotein (a) and the AvaII polymorphism of the low-density lipoprotein receptor gene influence the response of low-density lipoprotein cholesterol to pravastatin treatment

To investigate some individual and genetic factors that may influence the response of low-density lipoprotein cholesterol (LDL-C) to pravastatin treatment, we recruited 440 subjects with hypercholesterolemia (mean age, 57 years; 43% men) from 21 primary health care centers-outpatient clinics into a prospective, multicentered intervention trial. Pravastatin (20 mg/d) was prescribed for 16 weeks. The main outcome was the percentage variation in LDL-C concentration relative to baseline. Blood analyses and genotyping were performed centrally. The results indicated that LDL-C decreased by 20.5% (range, +21% to -66%) after pravastatin treatment. Baseline concentration of LDL-C (the higher the concentration, the greater the decrease), lipoprotein (a) levels (the lower the concentration, the greater the response), and Ava II polymorphism of the LDL-receptor gene significantly influenced the hypolipemic effect ( P < .001, P = .014, and P = .004, respectively). These 3 factors combined explained 10.6% of the variation in LDL-C response. Age, sex, smoking habit, alcohol consumption, body mass index, and apolipoprotein E genotype had no significant effect on response. We conclude that baseline levels of LDL-C and lipoprotein (a) together with the Ava II polymorphism of the LDL-receptor gene have a significant influence on the LDL-C response to pravastatin treatment in patients monitored in a standard primary health care outpatient clinic setting.

Pharmacogenetics of response to statins: Where do we stand?

Cardiovascular disease is one of the leading causes of death, especially in developed countries. Blood cholesterol lowering by way of statin therapy is a common risk-lowering therapy. The risk reduction for coronary artery disease for patients using statins is 27%. These reductions, however, are average effects for all patients included in the trials. There is notable interindividual variation in response to statins, and the origins of this variation are poorly understood. Pharmacogenetics seeks to determine the role of genetic factors in variation of drug response. In patients with primary hypercholesterolemia, 23 studies have examined the effects of genetic polymorphisms at 20 different loci on the lipid response to statin treatment, and 18 studies examined genetic polymorphisms involved in the benefits of statin therapy in the prevention of cardiovascular disease. Even though many studies have been performed, few results have been replicated. It is our contention that larger sample sizes and consideration of multiple genes are needed in the field of pharmacogenetics of statin response.

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.

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.

Seven DNA polymorphisms at the candidate genes of atherosclerosis in Brazilian women with angiographically documented coronary artery disease

The possible association of genetic markers at the apolipoprotein E (HhaI polymorphism), apolipoprotein B (XbaI, EcoRI and Ins/Del polymorphisms), and low-density lipoprotein receptor (LDLR) (AvaII, HincII and PvuII polymorphisms) with coronary artery disease (CAD) was evaluated in 50 Brazilian women with CAD diagnosed by angiography and in 100 healthy women (controls). The frequency of E3/E4 genotype for HhaI polymorphism at the Apo E gene was significantly higher in CAD patients than in controls (40% vs. 14%, respectively, P<0.001). Similarly, the X-X- genotype for XbaI polymorphism was more frequent in CAD individuals than controls (42% vs. 12%, P<0.0001). The A+A+ and P1P1 genotypes for AvaII and PvuII polymorphisms at the LDLR locus were also higher in CAD subjects than controls (44% vs. 16%, P<0.001 and 64% vs. 39%, P<0.05, respectively). The estimated relative risks for CAD in women carrying the E3/E4, X-X-, A+A+ and P1P1 genotypes were 4.1 [95% confidence interval (CI), 3.0-5.6], 5.3 (95% CI, 3.8-7.5), 4.1 (95% CI, 3.0-5.5), and 2.8 (95% CI, 2.2-3.6), respectively. This study demonstrates that Apo E, Apo B and LDLR gene polymorphisms are associated with CAD in Brazilian Caucasian women.

Association of the apolipoprotein B gene polymorphisms with cholesterol levels and response to fluvastatin in Brazilian individuals with high risk for coronary heart disease

The influence of genetic polymorphism of the apolipoprotein B on lipid metabolism and coronary heart disease (CHD) risk has been demonstrated in different populations, but few studies have shown the contribution of this risk factor in individuals from Brazil. The Ins/del, Xbal and EcoRI polymorphisms of apo B were evaluated in 93 controls and in 104 Caucasian individuals presenting with a high risk lipid profile (HR1) for CHD; 54 of these subjects (HR2) were treated with fluvastatin during 16 weeks. DNA polymorphisms of the apo B gene were analyzed by polymerase chain reaction-restriction fragment length polymorphism. The X(-)X(-) genotype for Xbal polymorphism was associated with higher serum concentrations of total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) (p<0.01) in women of the HR1 group. The Ins/del and EcoRI polymorphisms were not associated with variation of lipid profile. After treatment with fluvastatin, TC and LDL-C levels of HR2 individuals were reduced by 23% and 30%, respectively. Individuals with II genotype had significantly greater reduction (34%) of LDL-C than those with ID/DD genotypes (27%). These results indicate that the Xbal polymorphism is associated with variation of serum TC and LDL-C levels in Brazilian women with lipid profile of risk for CHD and the Ins/del polymorphism is associated with the therapeutic response to fluvastatin.