Role of common genetic polymorphisms in the LDL receptor gene in affecting plasma cholesterol levels in the general population

Post-Traumatic Stress Disorder Is Associated with Elevated Plasma Cholesterol in Female TT Homozygotes of LDLR rs5925

To explore the mechanism of inconsistent relationships between plasma lipid profiles and post-traumatic stress disorder (PTSD) reported before, we hypothesized that interplays might exist between PTSD and a variation of rs5925 at low-density lipoprotein receptor (LDLR) gene on plasma lipid profiles. To test our hypothesis, we analyzed the plasma lipid profiles of 709 high school pupils with various genotypes of LDLR rs5925 and with or without PTSD. The results demonstrated that PTSD prevalence in the C allele carriers was higher than that in the TT homozygotes regardless of gender. The C allele carriers had higher levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), ratios of TC to high-density lipoprotein cholesterol (TC/HDL-C) and LDL-C/HDL-C than the TT homozygotes in the male controls, and only higher TC in the female controls, but no differences in the male or female PTSD subjects. PTSD increased TC in the female TT homozygotes but not in the female C allele carriers. PTSD increased TC/HDL-C in the male TT homozygotes but not in the C allele carriers. These results suggest interactions between PTSD and LDLR rs5925 on plasma lipid profiles, which may be among the explanations for previously reported inconsistent relationships between LDLR rs5925 or PTSD and plasma lipid profiles, and facilitate the development of precision medicine interferences in hypercholesterolemia in individuals with different genetic backgrounds and psychiatric status. Psychiatric care or drug supplement may particularly be needed by female hypercholesterolemic subjects with the TT genotype of LDLR rs5925 in Chinese adolescents.

No association between LDL receptor and CETP genetic variants and atorvastatin response in Jordanian hyperlipidemic patients

OBJECTIVES

Atorvastatin is commonly used medication to achieve low levels of low-density lipoproteins (LDL). Cholesteryl ester transfer protein (CETP) and LDL receptor (LDLR) genetic variants can affect the cholesterol transport and hence may affect on atorvastatin response. This study aimed to investigate the influence of LDLR AvaII, CETP TaqIb, and Rs1532624 on the efficacy of 20 mg atorvastatin among Jordanian hyperlipidemic patients.

METHODS

One hundred and 50 blood samples were collected from hyperlipidemic patients in the University of Jordan Hospital. Polymerase chain reaction-restriction fragment length polymorphism was used for genotyping of LDLR AvaII and CETP TaqIb genetic variants. The genotyping of CETP Rs1532624 variant was done by Sanger DNA-Sequencing.

RESULTS

LDLR AvaII and CETP TaqIb and Rs1532624 variants showed a significant (p value < 0.05) association with the baseline of the LDL at the time of diagnoses. On the other hand, none of the tested genetic variants showed a significant (p value>0.05) association with LDL reduction after atorvastatin therapy.

CONCLUSIONS

Results demonstrated a significant association between the LDLR AvaII and CETP TaqIb, and Rs1532624 genetic variants with the LDL baseline level. However, the atorvastatin therapy among hyperlipidemic patients of Jordanian origin was not affected by any of the tested variants.

Role of low-density lipoprotein receptor rs5925 (1959C>T) gene polymorphism in pathogenesis of dyslipidemia among Egyptian lupus nephritis patients

Objectives

This study aims to investigate the prevalence of low-density lipoprotein receptor (LDL-R) rs5925 genetic variants and to evaluate their relationship with plasma lipid and kidney functions in lupus nephritis patients.

Patients and methods

Between September 2020 and June 2021, a total of 100 lupus nephritis patients (8 males, 92 females; mean age: 31.1±1.1 years; range, 20 to 67 years) and a total of 100 age- and sex-matched healthy volunteers (10 males, 90 females; mean age: 35.8±2.8 years; range, 21 to 65 years) were included. The gene polymorphism rs5925 (LDLR) was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Lipid profile and kidney functions were measured.

Results

Regarding rs5925 (LDLR), C allele was significantly higher among lupus nephritis patients (60%) compared to the control group (45%). While T allele was significantly lower in lupus nephritis patients (40%), compared to the control group (p=0.003). The plasma level of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) were significantly lower in lupus nephritis patients with TT and CT genotypes, compared to those with CC genotype. Moreover, atherogenic index of plasma (AIP) and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio were significantly lower in patients with TT genotype, compared to the patients with CC genotype. There was a strong and clear association between patients with renal biopsies grades III & IV & V and LDLR C allele (p=0.01, p=0.003, and p=0.004, respectively).

Conclusion

C allele is the significantly prevailed LDLR C1959T variant among lupus nephritis patients. Moreover, LDL-R genetic variant may be one of the non-immunological mechanisms implicated in the disturbed lipid profile among lupus nephritis patients. Profound dyslipidemia may partly underscore the deterioration of kidney function among lupus nephritis patients.

Effects of earthquake and related environmental factors on relationship of posttraumatic stress disorder with LDLR rs5925

To test the relationship not yet explored before among earthquake and related environmental factors, low-density lipoprotein receptor (LDLR) and posttraumatic stress disorder (PTSD), the genetic variation of LDLR rs5925 was selected and PTSD was examined by PTSD Checklist-Civilian Version (PCLC) in adolescents with different genotypes of LDLR rs5925 longitudinally at 6, 12 and 18 months after the 2008 Wenchuan earthquake. The C allele carriers were observed to have higher PTSD prevalence than the TT homozygotes in the male subjects, and higher PTSD prevalence and PCL-C scores in the female subjects only at 6 months. When compared to that at 12 months, decreased PTSD prevalence was observed at 18 months only in the female C allele carriers, but not in the female TT homozygotes or the male subjects. The potential risk factors of PTSD and predictors of PCL-C scores were different during the follow-up. LDLR rs5925 was one of the predictors for PCL-C scores at 6 and 12 months, and one of the potential factors for PTSD prevalence at 6 months. These results suggest that interactions may occur between earthquakes and other related environmental factors, which could affect the relationship of LDLR rs5925 with PTSD and be considered for individualized treatment.

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.

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.

Low density lipoprotein receptor gene Ava II polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

BACKGROUND

Several common genetic polymorphisms in the low density lipoprotein receptor (LDL-R) gene have associated with modifications of serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels, but the results are not consistent in different populations. Bai Ku Yao is a special subgroup of the Yao minority in China. The present study was undertaken to detect the association of LDL-R gene Ava Ⅱ polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

METHODS

A total of 1024 subjects of Bai Ku Yao and 792 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of the LDL-R gene Ava Ⅱ polymorphism was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

RESULTS

The levels of serum TC, high density lipoprotein cholesterol (HDL-C), LDL-C, apolipoprotein (Apo) A1 and the ratio of ApoA1 to ApoB were lower in Bai Ku Yao than in Han (P < 0.01 for all). The frequency of A⁻ and A+ alleles was 65.5% and 34.5% in Bai Ku Yao, and 80.7% and 19.3% in Han (P < 0.001); respectively. The frequency of A⁻A⁻, A⁻A+ and A+A+ genotypes was 42.6%, 45.9% and 11.5% in Bai Ku Yao, and 64.9%, 31.6% and 3.5% in Han (P < 0.001); respectively. There was also significant difference in the genotypic frequencies between males and females in Bai Ku Yao (P <0.05), and in the genotypic and allelic frequencies between normal LDL-C (≤ 3.20 mmol/L) and high LDL-C (> 3.20 mmol/L) subgroups in Bai Ku Yao (P < 0.05 for each) and between males and females in Han (P < 0.05 for each). The levels of LDL-C in males and TC and HDL-C in females were different among the three genotypes (P < 0.05 for all) in Bai Ku Yao, whereas the levels of HDL-C in males and HDL-C and ApoA1 in females were different among the three genotypes (P < 0.05-0.001) in Han. The subjects with A+A+ genotype had higher serum LDL-C, TC, HDL-C or ApoA1 levels than the subjects with A-A+ and A⁻A⁻ genotypes. Spearman rank correlation analysis revealed that the levels of LDL-C in Bai Ku Yao and HDL-C in Han were correlated with genotypes (P < 0.05 and P < 0.01; respectively).

CONCLUSIONS

The association of LDL-R gene Ava Ⅱ polymorphism and serum lipid levels is different between the Bai Ku Yao and Han populations. The discrepancy might partly result from different LDL-R gene Ava Ⅱ polymorphism or LDL-R gene-environmental interactions.

LDL-R AvaII and NcoI polymorphisms: an indirect risk factor for coronary heart disease among a Mendelian population of Delhi, India

AvaII and NcoI polymorphisms in the low-density lipoprotein receptor (LDL-R) gene are reported to alter cholesterol levels. Although found to be highly polymorphic worldwide, these mutations have not been validated in any Indian population. This case-control association study was conducted in an endogamous business community of Delhi. Blood samples from 100 cases and 100 age- and sex-matched controls belonging to the same ethnic group were subjected to biochemical and molecular analyses. Medical history and anthropometric measurements were taken from all the enrolled subjects. Linkage disequilibrium between the two polymorphisms was found to be significant (P = 0.0016). Significant variability was observed for the AvaII polymorphism among cases concerning waist-hip ratio, serum triglyceride, and low-density lipoprotein, which in turn was found to be associated with coronary heart disease.

TaqIB polymorphism in the CETP gene modulates the impact of HC/LF diet on the HDL profile in healthy Chinese young adults

The aim of this study was to investigate the interactions of genetic variants in the genes of cholesterol ester transfer protein (CETP) and low-density lipoprotein receptor (LDLR) with high carbohydrate and low fat (HC/LF) diet on lipid profiles in a young and healthy Chinese Han population. Fifty-six healthy subjects (22.89±1.80 years) were given washout diets of 31% fat and 54% carbohydrate for 7 days, followed by HC/LF diets of 15% fat and 70% carbohydrate for 6 days, with no total energy restriction. Serum lipid profiles at baseline, after washout and following HC/LF diets, as well as CETP and LDLR polymorphisms were analyzed. Carriers of B2 allele of CETP TaqIB polymorphism had significantly higher levels of high density lipoprotein cholesterol (HDL-C) and apo A-I in the whole study population after the diet intervention. Notably, males with CETP TaqIB B1B1 experienced significantly increased HDL-C and apo A-I after HC/LF diet. Regarding the LDLR Pvu II polymorphism, both P1P1 subjects and P2 carriers experienced decreased total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels after HC/LF diet with no statistically significant differences between the genotypes. Our results demonstrate that the elevated HDL-C levels after HC/LF diet in healthy Chinese Han youth are associated with CETP TaqI B2 allele while males with B1B1 genotype are more susceptible to the influence of HC/LF diet on their HDL-C levels. The decreased TC and LDL-C levels after HC/LF diet are not associated with LDLR Pvu II polymorphism.

Exploration of the relationship between phlegm-dampness constitution and polymorphism of low density lipoprotein receptor genes Pvu II and Ava II

OBJECTIVE

To explore the polymorphism of low density lipoprotein receptor (LDL-R) genes Pvu II and Ava II in a population with phlegm-dampness constitution (PDC).

METHODS

Polymorphism of LDL-R genes at Pvu II and Ava II of 48 persons with gentle constitution (GC) and 61 with PDC were analyzed with PCR-RELP technique, and their serum contents of lipids and glucose were determined and compared as well.

RESULTS

The A+ allelic and P-allelic frequency were higher and the P+ allelic frequency was lower in subjects with PDC than those in subjects with GC, which were 0.3083 vs 0.1771, 0.9098 vs 0.7708 and 0.0902 vs 0.2292, respectively, all showing significant difference between the two groups (P<0.05). Comparison of the two groups in serum levels of triglyceride (TG), fasting blood glucose, 2 h postprandial blood glucose, and 2 h postprandial insulin showed that all the parameters were higher in subjects with PDC than in subjects with GC respectively, showing significant difference (P<0.05).

CONCLUSION

PDC is related with the P- and A+ allelic frequency of higher LDL-R genes at Pvu II and Ava II, therefore, the polymorphism of LDL-R genes could be taken as one of the genetic markers for PDC, and humans with PDC are more liable to suffer from blood lipids and glucose disorder than those with GC.

Quantitative effects of common genetic variations in the 3′UTR of the human LDL-receptor gene and their associations with plasma lipid levels in the Atherosclerosis Risk in Communities study

The low-density lipoprotein receptor (LDLR) plays a pivotal role in cholesterol homeostasis. However, the role of genetic variations in the 3'UTR of the LDLR in relation to plasma cholesterol has been largely understudied. Six SNPs, G44243A, G44332A, C44506G, G44695A, C44857T and A44964G, within the 5' region of the 3'UTR fall into three common haplotypes, GGCGCA, AGCACG, and GGCGTA, occurring at frequencies of 0.45, 0.31 and 0.17, respectively, in Caucasians (n = 29) and 0.13, 0.13 and 0.38, respectively, in African Americans (n = 32), with three other haplotypes occurring at lesser frequencies. In a tissue culture based system, expression of a reporter gene carrying a 3'UTR that includes the 1 kb nucleotide sequences corresponding to the AGCACG or GGCGTA was 70 or 63%, respectively, of the same sequence with GGCGCA. Genotyping of two "haplotype tagging" SNPs, C44857T and A44964G, in the Atherosclerosis Risk in Communities (ARIC) study population showed that in Caucasians, but not in African Americans, the inferred TA haplotype had a significant LDL-cholesterol lowering effect. The adjusted LDL-cholesterol levels in the TA/TA diplotypes were lower by 6.10 mg/dl in men (P < 0.001) and by 4.63 mg/dl in women (P < 0.01) than in individuals with other diplotypes. Caucasian men homozygous for CA, in contrast, showed significantly higher LDL-cholesterol (P < 0.04), lower HDL-cholesterol (P < 0.02) and higher LDL/HDL ratios (P < 0.001). Thus our data shows that 3'UTR sequences that cause higher reporter gene expression in vitro are associated in Caucasians with plasma lipid profiles indicative of higher cardiovascular risk, suggesting that further studies of quantitative variants in the LDLR gene will be valuable.

Genetic study evaluating LDLR polymorphisms and Alzheimer's disease

We genotyped SNPs rs11668477, rs12983082, rs11669576, rs2738444, rs5925 and rs1433099 in 405 Finnish AD cases and 463 controls and conducted a single allele and genotypic distribution comparison and estimated the haplotype frequencies between cases and controls and evaluated the level of biomarkers in haplotype carriers. We observed that T allele of rs2738444 was overrepresented in AD women with p=0.014 (Bonferroni corrected p=0.252). A specific haplotype block consisting of SNPs rs11669576, rs2738444 and rs5925 was identified and in women the haplotype GTT was overrepresented in AD cases when compared to controls with p=0.008. We measured CSF Abeta(42), tau and phosphorylated tau (ptau) levels in a subgroup of cases and controls and found that some genotypes were associated with increased levels of tau and ptau or a decreased Abeta(42) level in women. The specific risk haplotype GTT was associated with an increased level of tau and ptau in both men and women. Our findings suggest that LDLR gene may be associated with AD risk and its CSF biomarkers, especially in women.

Association of genetic polymorphism of low-density lipoprotein receptor with chronic viral hepatitis C infection in Han Chinese

To study the association between the Ava II polymorphism at the low-density lipoprotein receptor (LDL-R) gene exon 13 locus and chronic hepatitis C virus (HCV) infection in the Han Chinese, 84 chronic HCV-infected patients without anti-viral treatment, and 72 healthy blood donors were studied. Polymerase chain reaction combined with restriction fragment length polymorphism (PCR-RFLP) was used to detect the Ava II polymorphism at the LDL-R gene exon 13 locus. The comparisons of genotype distribution and allele frequency between chronic HCV-infected patients and healthy controls showed statistically significant differences (P = 0.045 and P = 0.036, respectively). Additionally, the minor allele frequency (MAF) C in the healthy controls was higher than that in the chronic HCV-infected patients group. There was no significant difference (P = 0.130) when the genotype distribution was compared between chronic HCV-infected patients with HCV viremia and those without HCV viremia. However, the comparisons of allele frequency between the two groups showed a statistically significant difference (P = 0.047), and the MAF C in HCV RNA negative group was significantly higher than that in HCV RNA positive group. There were no significant differences in genotype distribution and allele frequency of the Ava II restriction site at the LDL-R gene exon 13 locus between patients with chronic HCV infection and those with HCV-associated cirrhosis as well as between patients with normal serum alanine aminotransferase (ALT) and those with abnormal ALT levels. These results suggest that the Han Chinese have Ava II polymorphism at the LDL-R gene exon 13 locus. The Ava II polymorphism at the LDL-R gene exon 13 locus showed a statistically significant difference between chronic HCV-infected patients and healthy controls, indicating a significant contribution of the Ava II polymorphism in susceptibility to HCV infection in these patients. The MAF C in HCV RNA negative group was higher than that in HCV RNA positive group, suggesting that the Ava II polymorphism might also be associated with viremia in patients with HCV infection.

Functional interaction between APOE4 and LDL receptor isoforms in Alzheimer's disease

BACKGROUND

Multiple genes have been provisionally associated with Alzheimer's disease, including the coding polymorphisms in exons 8 and 13 in the low density lipoprotein receptor gene (LDLR), situated on chromosome 19p13.2.

METHODS

The sample groups consisted of 180 AD patients and 141 control spouses. We carried out genotyping of LDLR8 and LDLR13.

RESULTS

The LDLR8 GG genotype was common, found in 84% of the unaffected control subjects and 91% of the AD patients in our study. There was a ninefold elevation in risk associated with GG:CC versus A- and T- among APOE4+ subjects when compared with APOE4- subjects (odds ratio 9.3; 95% confidence interval 1.8 to 48.2). With the additional information on LDLR polymorphism, we defined an overall 12 fold elevation in risk for APOE4 in combination with LDLR GG:CC (11.9; 2.8 to 50.0; Fisher's exact test, p = 0.0002; standard power 0.999), compared with other subjects lacking all three of these polymorphisms.

CONCLUSION

These results imply a functional interaction between ApoE and LDL receptor proteins that determines risk for Alzheimer's disease.

Combined effects of apoE-CI-CII cluster and LDL-R gene polymorphisms on chromosome 19 and coronary artery disease risk

OBJECTIVE

To investigate associations of gene polymorphisms of the apoE-CI-CII gene cluster and the LDL-R gene on coronary artery disease (CAD) and their interactions with alcohol drinking and smoking in the Chinese Han population.

METHODS

A questionnaire survey of the behaviors of smoking and drinking, dietary patterns and anamnesis was conducted among 203 patients of CAD, aged 65.0 +/- 11.1 years, and 365 controls, aged 63.6 +/- 12.0 years. Peripheral blood samples were colleted and the total DNA was extracted. The apoE genotypes were identified by multiplex amplification refractory mutation system (multi-AMRS), the apoCI promoter polymorphisms and AvaII polymorphisms of the apoCII and LDL-R gene were detected by using PCR-RFLP. Pairwise linkage disequilibrium coefficients (D, D') were estimated by the LINKAGE program. The interactions between genes with alcohol drinking and smoking were analyzed by using multivariate logistic regression models.

RESULTS

The differences of systolic/diastolic blood pressure, total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) concentrations, smoking and drinking were significant between subjects with CAD and controls. The frequencies of apoE gene epsilon 3/4 genotype (25.9%) and epsilon 4 (13.9%) in CAD were significantly higher than those in controls (12.5% and 6.9%, respectively, p < 0.05). A significant difference was also found for the apoCI locus, the frequencies of H2 allele were 20.5% in the CAD and 11.3% in the control. Linkage disequilibrium coefficient D' was 0.672 (p < 0.01) between apoE and apoCI genes. Significant differences for a deficit of epsilon 3-H1-T1 and excess of epsilon 4-H2-T1 was found in CAD by estimation of the haplotype frequencies. After control for possible confounding factors, the multivariate logistic analysis showed that epsilon 4, H2 allele, smoking and drinking were risk factors of CAD. A significant interaction among epsilon 4, H2 and smoking was observed (OR 18.3, 95% CI: 2.35-150.81, p < 0.05), it was a multiplicative model. An additive model was shown among epsilon 4, H2 and drinking (OR12.7, 95% CI: 2.8-58.6, p < 0.05).

CONCLUSION

The results suggested that both apoE and apoCI on chromosome 19 were the susceptibility locus for CAD, their linkage disequilibrium should be responsible for the development of CAD. Drinking and smoking enhance the genetic predisposition to CAD.

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.

Are common disease susceptibility alleles the same in outbred and founder populations?

Founder populations have been the subjects of complex disease studies because of their decreased genetic heterogeneity, increased linkage disequilibrium and more homogeneous environmental exposures. However, it is possible that disease alleles identified in founder populations may not contribute significantly to susceptibility in outbred populations. In this study we examine the Hutterites, a founder population of European descent, for 103 polymorphisms in 66 genes that are candidates for cardiovascular or inflammatory diseases. We compare the frequencies of alleles at these loci in the Hutterites to their frequencies in outbred European-American populations and test for associations with cardiovascular disease-associated phenotypes in the Hutterites. We show that alleles at these loci are found at similar frequencies in the Hutterites and in outbred populations. In addition, we report associations between 39 alleles or haplotypes and cardiovascular disease phenotypes (P<0.05), with five loci remaining significant after adjusting for multiple comparisons. These data indicate that this founder population is informative and offers considerable advantages for genetic studies of common complex diseases.

Potential genetic markers of sporadic Alzheimer's dementia

Polymorphisms within the genes encoding apolipoprotein E (ApoE), apolipoprotein CI (ApoCI), alpha1-antichymotrypsin (ACT), the low-density lipoprotein (LDL) receptor and lipoprotein lipase were investigated in patients suffering from Alzheimer's dementia and non-demented psychiatric patients as control subjects. The ApoE allele 4, well known as a risk factor in Alzheimer's disease, and the ApoCI allele A2, which is closely linked to the ApoE allele 4, were found elevated in the index group. Concerning the polymorphism within exon 8 of the LDL receptor (alanin/threonin), there was also a predominance of the allele carrying threonin in the index group, which barely missed significance. Distribution of the polymorphisms of ACT and lipoprotein lipase were similar in both groups investigated. We conclude that, apart from the ApoE allele 4, other genetically regulated factors like ApoCI and the LDL receptor modulate the individual risk for Alzheimer's disease.

Mutations in the low-density-lipoprotein receptor gene in German patients with familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is an autosomal dominant disorder of lipid metabolism characterized by elevated low-density lipoproteins (LDL), the formation of tendon and skin xanthomata and the development of premature coronary atherosclerosis. It is caused by a defect in the receptor-mediated hepatic uptake of LDL due to mutations in the LDL receptor. In 25 FH families with a total of 160 members and in two individuals without available relatives, all of German origin, we identified LDL receptor mutations by a multiplex-PCR-based single-strand conformation polymorphism method followed by direct sequencing. Of the 24 mutations found, 15 are missense mutations, 2 are nonsense mutations, 4 are small deletions or insertions leading to frameshifts, 2 are an in-frame insertion and deletion, respectively, and one is a splice site mutation. Propositi carrying mutations that are known to completely abolish receptor function (nonsense and frameshift mutations, missense mutation V480M) had significantly higher untreated total and LDL-cholesterol levels compared to those patients carrying missense and in-frame insertion mutations of unknown functional consequence, which may lead to either reduced or completely abolished receptor function (11.30+/-1.64 vs 9.76+/-1.50 mmol/L, and 9.39+/-1.23 vs 7.99+/-1.45 mmol/L, respectively). These results confirm the clinical and molecular heterogeneity of FH and the influence of different functional classes of mutations on lipid values.

Pvu II intron 15 polymorphism at the LDL receptor gene is associated with differences in serum lipid concentrations in subjects with low and high risk for coronary artery disease from Brazil

Coronary artery disease (CAD) has a high prevalence in the Brazilian population. Nevertheless, studies of genetic risk factors for CAD in this country have not been sufficiently conducted. We used the Pvu II polymorphism (intron 15) at the low-density lipoprotein receptor (LDLR) gene to study the effect of variation at this locus in determining plasma lipid concentrations in 128 white subjects presenting a lipid profile suggesting high risk for CAD (HRG) and 100 white normolipidemic individuals (controls, CG). The Pvu II polymorphism was detected by PCR-RFLP. The P1P1 genotype for Pvu II polymorphism (homozygous for absence of restriction site) was greater in HRG individuals than in CG subjects (57% vs. 38%, P<0.05). Moreover, the P1P1 genotype was strongly associated with high concentrations of total cholesterol (P=0.0001), triglycerides (P=0. 0295), LDL-C (P=0.0001), and VLDL-C concentrations (P=0.0280) and lower HDL-C concentrations (P=0.0051) in HRG subjects. Similarly, the CG individuals with P1P1 genotype presented high concentrations of total cholesterol and LDL-C compared to other genotypes (P=0. 0001). This study demonstrates the influence of Pvu II polymorphism of the LDLR on serum lipid concentrations of individuals with low and high risk for CAD from Brazil.

Effects of Ava II and Hinc II polymorphisms at the LDL receptor gene on serum lipid levels of Brazilian individuals with high risk for coronary heart disease

Coronary heart disease (CHD) has presented high prevalence in the Brazilian population. Nevertheless, studies of genetic risk factors for CHD in our country are insufficiently carried out. We have investigated the effects of Ava II (exon 13) and Hinc II (exon 12) polymorphisms at the low-density lipoprotein receptor (LDLR) gene on circulating lipids of 170 white unrelated individuals presenting a lipid profile with high risk for CHD (HRG) and 130 controls (CG) from São Paulo City, Brazil. Ava II and Hinc II polymorphic regions at the LDLR gene were amplified by PCR and analyzed by enzymatic isotyping. The frequency of the genotypes A+A+ (Ava II) and H+H+ (Hinc II) was greater in HRG group compared to that of the controls (32 vs. 16% and 32 vs. 18%, respectively). Moreover, in the HRG group, A+A+ and H+H+ genotypes were associated with high concentrations of total cholesterol and LDL-C in serum (P = 0.0001). Our results indicate that Ava II and Hinc II polymorphisms at the LDLR locus contribute to the variability of total cholesterol and LDL-C levels in HRG individuals. These data suggest that the LDLR polymorphism remains a useful genetic marker for predicting CHD risk.

Genetic association studies between dementia of the Alzheimer's type and three receptors for apolipoprotein E in a Caucasian population

The epsilon 4 allele of the apolipoprotein E gene (ApoE) is associated with an increased risk for sporadic and some familial forms of Alzheimer's disease (AD) but the precise mechanism of pathogenesis is unknown. ApoE is a ligand for at least three receptors in the central nervous system, low density lipoprotein receptor (LDL-R), very low density lipoprotein receptor VLDL-R and low density lipoprotein-like receptor (LRP). We have tested for association between these receptors and dementia of the Alzheimer's type (DAT) in a clinically based sample of Caucasian cases and age-matched controls. In contrast to findings in a Japanese cohort we detected no association between DAT and a polymorphism in the VLDL-R gene. No association was detected with the LDL-R gene. We observed a possible association between the 87 allele of a polymorphism within the LRP gene and DAT which remained significant after correction for multiple testing. When the effects of known risk factors for AD such as ApoE epsilon 4 were applied, the effect of LRP no longer reached conventional levels of statistical significance. Nevertheless, LRP is a plausible candidate gene and we may be observing a minor risk factor that will require further examination in other large independent samples to assess whether it truly modifies susceptibility to DAT.

Influence of genetic variability in the nondeletion LDL-receptor allele on phenotypic variation in French-Canadian familial hypercholesterolemia heterozygotes sharing a 'null' LDL-receptor gene defect

We investigated the associations between low density lipoprotein (LDL)-receptor gene haplotypes and lipid and lipoprotein levels in French-Canadian individuals with familial hypercholesterolemia (FH). The 112 unrelated patients studied shared the same > 10 Kb deletion in the 5' region of the LDL-receptor gene, leading to a null allele. Support for the hypothesis that the deletion is carried on only one LDL-receptor restriction fragment length polymorphism (RFLP) haplotype in this sample has previously been demonstrated [1]. We studied associations of genetic variability in DNA polymorphisms of the nondeletion LDL-receptor allele with variation in plasma lipid levels in these patients heterozygous for the deletion. All analyses were done separately in males and females. The traits were adjusted for variation in the concomitants age, height and weight, and for variation in apolipoprotein (apo) E phenotype, and then the association between variability in haplotypes defined by two RFLP loci and variation in trait levels were tested. The results indicated that in this sample of French-Canadian > 10 Kb deletion FH heterozygotes, variability at the LDL-receptor gene contributes to quantitative variation in measures of lipid metabolism and that the effects are different in males and females. The results indicated that variability at the LDL-receptor gene defined by two RFLP loci contributes to quantitative variation in high density lipoprotein (HDL)-cholesterol and LDL-cholesterol concentrations in French-Canadian FH women heterozygous for the > 10 Kb deletion and not in men.

Influence of apolipoprotein E genotypes on plasma lipid and lipoprotein concentrations: results from a segregation analysis in pedigrees with molecularly defined familial hypercholesterolemia

Familial hypercholesterolemia (FH) is a monogenic disorder caused by mutations in the low-density lipoprotein (LDL) receptor gene. Large variations in plasma lipids and lipoprotein levels have been observed in FH families. These may be caused by other environmental and genetic factors of which apolipoprotein E (apo E) is a candidate. The possible influence of apo E polymorphism on components of variation in plasma LDL-C, triglycerides, high-density lipoprotein cholesterol (HDL-C), and lipoprotein(a) (Lp(a)) levels was investigated in 235 members of 14 families with FH. Sex-and age-adjusted mean LDL-C was influenced significantly by the apo E genotype in non-FH subjects (P <or= .01), and a similar trend was observed in FH cases. Mean plasma levels of triglyceride, HDL-C, and Lp(a) were not significantly different across the apo E genotypes in FH and in non-FH family members. Complex segregation analysis was first applied to these sex- and age-adjusted data. In addition to the major gene involved in LDL-C levels (i.e., the LDL receptor gene), there was evidence for a non-transmitted environmental major factor in addition to polygenic effect that explained the mixture of distributions in TG and a major effect in addition to polygenic loci which influenced Lp(a) levels. There was no evidence for a single major factor controlling HDL-C levels in these pedigrees. When the segregation models allowed apo E regression coefficients to be ousiotype (class) specific, the results suggested that apo E genotypes have a significant effect on LDL-C, TG, and Lp(a) levels. In conclusion, the analysis presented here supports the concept that the apo E gene has an important role in the regulation of plasma lipid and lipoproteins in FH.