ABCG8 gene polymorphisms, plasma cholesterol concentrations, and risk of cardiovascular disease in familial hypercholesterolemia.

Elevated plasma plant sterol concentrations may be a risk factor of cardiovascular disease (CVD). Polymorphisms in the ABCG8 gene have been identified that contribute to the variation in plasma concentrations of plant sterols. However, data on the direct relationship of ABCG8 gene polymorphisms with CVD are lacking. Therefore, we examined associations between the D19H and T400K polymorphisms in the ABCG8 gene and CVD in a large cohort study of 2012 patients with heterozygous familial hypercholesterolemia (FH). A total of 244 individuals carried one or two alleles of the D19H variant and 568 individuals the T400K variant. During 94,809 person years, 648 (32.2%) individuals developed CVD of which coronary heart disease (CHD) was the most frequent cardiovascular event (N=553). In a Cox proportional hazard regression model adjusted for relevant cardiovascular risk factors, the D19H polymorphism was not associated with total CVD risk (p=0.2), but there was evidence of an association with higher risk of CHD (RR 1.42, CI 1.04-1.95; p=0.03). We observed no relationship between the T400K polymorphism and cardiovascular endpoints (p>0.1). However, FH individuals carrying the risk genotype for both ABCG8 variants had an increased risk of CVD (RR 1.57, 95% CI 1.13-2.18; p=0.01) and CHD (RR 1.72, 95% CI 1.23-2.41; p=0.002). In conclusion, our data suggest that genetic variation in the ABCG8 gene may influence the burden of atherosclerosis.

Complement factor H Y402H decreases cardiovascular disease risk in patients with familial hypercholesterolaemia.

AIMS: Activation of the complement system seems an important link between inflammation and atherogenesis. The Y402H polymorphism of complement factor H (CFH) has been associated with cardiovascular events, but results are conflicting and possibly modified by age of onset of cardiovascular disease (CVD). METHODS AND RESULTS: We determined whether or not the Y402H polymorphism influenced CVD risk in a multicentre cohort study involving 2,016 unrelated patients with familial hypercholesterolaemia (FH), who have an extremely increased susceptibility to premature CVD. We identified 261 individuals who were homozygous for the polymorphism (CC genotype; 12.9%), 929 individuals who were heterozygous (TC genotype; 46.1%), and 826 individuals carried the wild-type (TT genotype; 41.0%). During 95 115 person years, 644 patients had a cardiovascular event. Carriers of the CC genotype had a decreased risk of CVD (hazard ratio 0.67, 95% confidence interval 0.51-0.87; P = 0.003) relative to the other genotype groups. This association was unaltered after adjustment for clinically relevant cardiovascular risk factors or age effects. CONCLUSION: Among patients with severely increased risk of early onset CVD, the Y402H CFH variant was inversely associated with susceptibility to CVD. This suggests that CFH is a modifier gene of CVD.

Two common haplotypes of the glucocorticoid receptor gene are associated with increased susceptibility to cardiovascular disease in men with familial hypercholesterolemia.

CONTEXT: Glucocorticoids contribute to the development of atherosclerosis. Four polymorphisms in the glucocorticoid receptor (GR) gene have been reported to alter glucocorticoid sensitivity and have been associated with cardiovascular risk factors. Studies on the relationship between these GR variants and cardiovascular disease (CVD) risk, however, have yielded conflicting results. OBJECTIVE: We sought to determine whether haplotypes based on functional polymorphisms in the GR gene influenced susceptibility to CVD in a high-risk population. DESIGN, SETTING, AND PARTICIPANTS: In a multicenter cohort study, 1830 patients with heterozygous familial hypercholesterolemia were genotyped for the functional ER22/23EK, N363S, BclI, and 9beta variants. We analyzed the combined effect of all GR variants by constructing haplotypes and using a Cox proportional hazards regression model with adjustment for year of birth and smoking. The analyses were stratified for sex. MAIN OUTCOME MEASURES: The primary outcome measure was CVD defined as coronary, cerebral, and peripheral artery disease. RESULTS: A total of 359 men (40.8%) and 224 women (23.6%) had a cardiovascular event. In men, the BclI haplotype was associated with a 34% higher CVD risk (confidence interval 1.02-1.76; P = 0.03) and the 9beta haplotype with a 41% higher CVD risk (confidence interval 1.02-1.94; P = 0.04). In women, none of the GR haplotypes was significantly related with CVD. We did not find differences in cardiovascular risk factors between GR haplotypes. CONCLUSIONS: In this large cohort of high-risk individuals, two common haplotypes in the GR gene modified CVD susceptibility among men.

A functional polymorphism in the glucocorticoid receptor gene and its relation to cardiovascular disease risk in familial hypercholesterolemia.

CONTEXT: Individuals with the functional ER22/23EK variant in the glucocorticoid receptor gene are relatively resistant to the downstream consequences of glucocorticoids. Evidence suggests that carriers have a more favorable cardiovascular risk profile, but the relationship between this ER22/23EK variant and cardiovascular disease has not been hitherto assessed. OBJECTIVE: We, therefore, determined whether carriership of the ER22/23EK improves cardiovascular disease risk in patients with severe hypercholesterolemia. DESIGN, SETTING, AND PARTICIPANTS: In a multicenter cohort study, 2024 patients with heterozygous familial hypercholesterolemia, aged 18 yr and older, were genotyped for the ER22/23EK polymorphism. Patients were identified at lipid clinics throughout The Netherlands between 1989 and 2002. MAIN OUTCOME MEASURES: The primary outcome measure was cardiovascular disease. RESULTS: Seventy-six (7.8%) of 977 men and 72 (6.9%) of 1047 women were carriers of the ER22/23EK variant. A total of 395 men and 247 women had a cardiovascular event. In contrast to expected results, we observed no significant association of the ER22/23EK variant with cardiovascular disease risk (men: relative risk, 0.75; 95% confidence interval, 0.50-1.14; P = 0.2; women: relative risk, 1.37; 95% confidence interval, 0.82-2.28; P = 0.2). However, we found a significant interaction between gender and the polymorphism on cardiovascular disease (P = 0.02). CONCLUSIONS: In this large cohort of individuals with very high risk of cardiovascular disease, the association between the functional ER22/23EK polymorphism and cardiovascular risk was not significant overall, although it varied significantly by gender.

Low-density lipoprotein receptor genotype and response to pravastatin in children with familial hypercholesterolemia: substudy of an intima-media thickness trial.

BACKGROUND: The lipid-lowering effects of statin therapy show considerable interindividual variation in patients with familial hypercholesterolemia (FH). Whether the type of LDL receptor mutation predicts the response to statin treatment is not yet established. We analyzed the relationship between LDL receptor genotype and response to pravastatin treatment in children with FH using carotid intima-media thickness (IMT) to measure efficacy. METHODS AND RESULTS: In a randomized, placebo-controlled, double-blind, 2-year trial with pravastatin, 193 children had genetically confirmed FH and were included in the present substudy. At baseline, children with null alleles had higher LDL cholesterol levels (difference, 0.94+/-0.19 mmol/L [SEM]; P<0.001) and a greater carotid IMT (difference, 0.019+/-0.01 mm; P=0.02) compared with children with receptor-defective mutations. The decrease in carotid IMT during the trial was not significantly different in children with null alleles and receptor-defective mutations (0.018+/-0.012 and 0.012+/-0.010 mm; 2-way ANCOVA, P=0.7). After 2 years of treatment, the children with null alleles continued to have greater carotid IMT than children with receptor-defective mutations (difference, 0.016+/-0.01 mm; P=0.02). LDL cholesterol lowering tended to be less in carriers of null alleles compared with carriers of receptor-defective mutations (1.30+/-0.25 and 1.85+/-0.20 mmol/L; 2-way ANCOVA, P=0.08). CONCLUSIONS: In FH children, we found that the null allele genotype was associated with a greater carotid IMT, higher LDL cholesterol levels, and a nonsignificant tendency to attenuated LDL cholesterol lowering compared with receptor-defective mutations. Null alleles identify FH patients at the highest cardiovascular disease risk who may benefit from more aggressive treatment started in childhood.

Effect of low-density lipoprotein receptor mutation on lipoproteins and cardiovascular disease risk: a parent-offspring study.

Studies on the clinical consequences of different low-density lipoprotein (LDL) receptor genotypes in adult patients have yielded conflicting results. We hypothesized that children with familial hypercholesterolemia (FH) provide a better model to perform genotype-phenotype analyses than adults. We tested this hypothesis and assessed the effect of LDL receptor genotypes on lipoprotein levels and on parental risk of cardiovascular disease (CVD) in a pediatric FH cohort. We identified 75 different LDL receptor mutations in 645 children with heterozygous FH; in these children, null alleles were clearly associated with more elevated LDL cholesterol levels compared to receptor-defective mutations. Familial factors explained 50.4% of the variation in LDL cholesterol levels of this pediatric cohort compared to only 9.5% in adults. Parental CVD risk was not significantly different between carriers of null alleles and receptor-defective mutations (RR, 1.22; 95% CI, 0.76-1.95; p=0.4). The N543H/2393del9 mutation was associated with a less deteriorated lipid profile and the parents had less often CVD relative to parents with other mutations (RR, 0.39; 95% CI, 0.20-0.78; p=0.008). We could confirm that children with FH provide a better model to perform genotype-phenotype analyses. In particular, children with null alleles had significantly more elevated LDL cholesterol levels than carriers of other alleles but this was not associated with higher risk of CVD in the parents. Nonetheless, a specific LDL receptor mutation was associated with less deteriorated lipoprotein levels and a milder CVD risk.