Adenine for guanine substitution -78 base pairs 5' to the apolipoprotein (APO) A-I gene: relation with high density lipoprotein cholesterol and APO A-I concentrations

[－75 G/A Polymorphism of Apolipoprotein A1 Gene Promoter Region in Normal Pregnant Women and Patients With Gestational Diabetes Mellitus]

Objective

To investigate the －75 G/A single-nucleotide polymorphism in the promoter region of apolipoprotein A1 gene (apoA1) and its association with gestational diabetes mellitus (GDM) in pregnant women and to provide references for the exploration in the molecular genetic basis of GDM.

Methods

A total of 626 GDM patients and 1022 normal pregnant women, ie, the controls, were included in the study. The genotyping of apoA1 －75 G/A polymorphism was performed by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. Total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and glucose (Glu) were measured by enzymatic methods. Plasma insulin (INS) was measured by chemiluminescence immunoassay. The protein levels of apoA1 and apoB were measured by the turbidimetric immunoassay.

Results

Allele frequencies of G and A were 0.718 and 0.282 in the GDM group and 0.713 and 0.287 in the control group, respectively. Distribution of the genotype frequencies was found to be in Hardy-Weinberg equilibrium in both the GDM and control groups. There was no significant difference in the frequencies of alleles G and A and the genotypes of apoA1 －75 G/A polymorphism between the GDM and the control group (P>0.05). In the GDM group, the carriers with the genotype AA were associated with significantly higher levels of TC, HDL-C, and apoA1 than those with genotypes GG and GA did (all P<0.05). After the GDM patients were divided into obese and non-obese subgroups, the genotype-related apoA1 variation was observed only in obese patients, while the genotype-related TC and HDL-C variations were evident in non-obese patients (P<0.05). In the control group, carriers of genotypes AA and GA had higher systolic blood pressure (SBP) and HDL-C than the carriers of genotype GG did (all P<0.05). Carriers of genotypes AA had significantly lower Glu levels than carriers of genotypes GG and GA did (P<0.05). The control subjects were further divided into subgroups according to their body mass index (BMI). Analysis of the subgroups showed that AA carriers were associated with higher SBP levels in the obese control women only, while lower Glu levels were evident in both obese and non-obese control women.

Conclusion

These results suggest that －75 G/A polymorphism in the apoA1 gene is not associated with GDM. However, the genetic variation is closed associated with the plasma apoA1, HDL-C, and TC levels in GDM patients and plasma HDL-C, Glu, and SBP levels in the control subjects. The apoA1 variant-associated lipids and SBP variation is BMI dependent in both groups.

Effect of apolipoprotein A1 genetic polymorphisms on lipid profiles and the risk of coronary artery disease

Background

The disorder of lipid metabolism and genetic predisposition are major risk factors for coronary artery disease (CAD). Variants in the apolipoprotein A1 (APOA1) gene play an important role in the regulation of lipids. The objective of the present study was to investigate the effect of two polymorphisms (-75 G/A and +83 C/T) of APOA1 on lipid profiles and the risk of CAD.

Methods

A total number of 300 subjects with CAD and 300 age and sex matched healthy controls were enrolled for the study. Genotyping of the APOA1 was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

The frequencies of APOA1 -75 AA genotype [odds ratio (OR) =0.50, 95 % confidence interval (CI) = 0.28, 0.88; P = 0.02] and APOA1 -75 A allele (OR =0.76, 95 % CI = 0.59, 0.98; P = 0.04) were significantly lower in CAD than in controls. The APOA1 -75 A allele was significantly associated with increasing serum concentrations of ApoA1 and high-density lipoprotein cholesterol (HDL-C) (P < 0.001).

Conclusions

The individuals with the APOA1 -75 A allele were likely to have a lower risk of CAD as a result of its effect on higher serum concentrations of ApoA1 and HDL-C.

Can novel Apo A-I polymorphisms be responsible for low HDL in South Asian immigrants?

Coronary artery disease (CAD) is the leading cause of death in the world. Even though its rates have decreased worldwide over the past 30 years, event rates are still high in South Asians. South Asians are known to have low high-density lipoprotein (HDL) levels. The objective of this study was to identify Apolipoprotein A-I (Apo A-I) polymorphisms, the main protein component of HDL and explore its association with low HDL levels in South Asians. A pilot study on 30 South Asians was conducted and 12-h fasting samples for C-reactive protein, total cholesterol, HDL, low-density lipoprotein (LDL), triglycerides, Lipoprotein (a), Insulin, glucose levels, DNA extraction, and sequencing of Apo A-I gene were done. DNA sequencing revealed six novel Apo A-I single nucleotide polymorphisms (SNPs) in South Asians, one of which (rs 35293760, C938T) was significantly associated with low (<40 mg/dl) HDL levels (P = 0.004). The association was also seen with total cholesterol (P = 0.026) and LDL levels (P = 0.032). This pilot work has highlighted some of the gene-environment associations that could be responsible for low HDL and may be excess CAD in South Asians. Further larger studies are required to explore and uncover these associations that could be responsible for excess CAD risk in South Asians.

Synergistic effect between apolipoprotein E and apolipoprotein A1 gene polymorphisms in the risk for coronary artery disease

Alterations in lipid metabolism and genetic predisposition are major risk factors for coronary artery disease (CAD). Variations in genes involved in lipid metabolism may act synergistically to confer risk or protection against CAD. The objective of the present study was to determine such interactions in variants of apolipoprotein E and apolipoprotein A1 genes. One hundred and forty subjects with clinically confirmed CAD and 100 unrelated normal subjects participated in the study. Multiple regression analysis was used to relate lipid and apolipoprotein profiles with genotypes. Odd ratios were calculated for various combinations of ApoE and ApoA1 genotypes. Prevalence of ApoE 'E4' and ApoA1 'A' and 'T' alleles was significantly higher in patients than controls. Serum apolipoprotein E and apolipoprotein A1 levels were significantly lower in CAD patients than controls. When lipid parameters were related to genotypes, the polymorphisms associated to various markers were in agreement with previous reports. ApoE 2/4 genotype in combination with either ApoA1 heterozygous GA or CT genotype conferred higher risk of CAD. E3 allele in homozygous or heterozygous state in combination with ApoA1+83 CC genotype conferred highest protection (P < 0.05). Thus, it appears that ApoE and ApoA1 gene variants may act synergistically to associate with risk and protection against CAD.

Genetic association study of APOA1/C3/A4/A5 gene cluster and haplotypes on triglyceride and HDL cholesterol in a community-based population

BACKGROUND

Polymorphism of apolipoprotein A1/C3/A4/A5 gene cluster affected lipid profiles in general population. We reported 6 polymorphisms, APOA1 -75G>A, APOA1 83C>T, APOC3 3175C>G, APOC3 3206G>T, APOA4 127A>G, and APOA5 553G>T in APOA1/C3/A4/A5 gene and the haplotype structures on triglyceride and HDL traits among ethnic Chinese.

RESULTS

Overall, there were statistically significant differences in the distribution of APOA1 -75G>A and APOA5 +553G>T genotypes comparing cases with control subjects. For the APOA1 -75 SNP, a lower risk of triglyceride/HDL among subjects with A/A genotype compared with those with the G/G genotype (odds ratio, OR=0.39, 95% CI 0.16-0.92, P=0.04). However, the risk magnitude reduced after multivariate adjustments. For continuous traits, we found that only in APOA5 +553 T allele carriers showed a significant higher triglyceride and a significant lower HDL cholesterol level than subjects with APOA5 +553 G/G genotypes. There were significant differences in overall haplotype frequencies between case and control subjects (P<0.001).

CONCLUSION

There is an important role of APOA1/C3/A4/A5 gene polymorphisms and haplotypes in the development of high triglyceride/HDL ratio in Chinese.

ApolipoproteinA1-75 G/A (M1-) polymorphism and lipoprotein(a); anti- vs. pro-Atherogenic properties

BACKGROUND

ApolipoproteinA1 (apoA1) is the major apoprotein constituent of high-density-lipoprotein(HDL). The relationship of apoA1 -75 bp(M1-) allele polymorphism with lipoprotein phenotype and cardiovascular disease (CVD) remain unclear. Overnight fasting blood samples were collected from a cohort of high-risk Omani population, 90 non-diabetic subjects and 149 type 2 diabetes mellitus (T2DM) subjects for genotype and phenotype studies.

RESULTS

The M1+ and M1- alleles frequencies were 0.808 and 0.192 for M1+ and M1-, respectively, comparable to the frequency of apoA1 (M1+ and M1-) amongst a healthy Omani population, 0.788 and 0.212, respectively. The frequencies of the hetero- and homozygous subjects for the MspI polymorphism at -75 (M1-) of the apoA1 gene were in Hardy-Weinberg equilibrium. The mean Lp(a) concentration was significantly higher(P = 0.02) in subjects carrying M1- allele compared to M1+ allele of the APOA1 gene with an odd ratio of 2.3(95% CI, 1.13-14.3), irrespective of gender and the diabetic status.

CONCLUSION

ApolipoproteinA1-75 G/A (M1-) polymorphism is relatively common and is positively associated with Lp(a) and therefore, may confer a potential risk for cardiovascular disease (CVD).

Apolipoprotein AI-CIII-AIV gene cluster polymorphisms in relation to cholesterol gallstone

OBJECTIVE

To investigate the frequency of variants at Xmn I, Msp I sites of apolipoprotein (Apo), A I-CIII-AIV gene cluster, and its relation to cholesterol gallstones in Chinese patients.

METHODS

Restriction fragment length polymorphisms (RFLP) at Xmn I, Msp I sites of ApoAI-CIII-AIV gene cluster were studied using a polymerase chain reaction (PCR) in 161 patients with cholesterol gallstones and 94 healthy subjects from a Chinese population in Sichuan Province.

RESULTS

In both the cholesterol gallstone group and the healthy control group, X1 and M1 alleles were the major alleles and homozygous X1X1 and M1M1 genotypes were the most frequent. However, the frequency of X2 allele mutation in female patients of the cholesterol gallstones group was significantly higher than that in women in the healthy control group (P<0.05), but no difference was found in the frequency of M2 alleles mutation (P>0.05).

CONCLUSION

The data showed that Xmn I RFLP of ApoAI-CIII-AIV gene cluster is associated to some extent with cholesterol gallstones in female Chinese patients.

Genetic interactions with diet influence the risk of cardiovascular disease

Single-nucleotide polymorphisms are an integral component of the evolutionary process that over millennia have resulted from the interaction between the environment and the human genome. Relatively recent changes in diet have upset this interaction with respect to the nutritional environment, but nutritional science is beginning to better understand the interaction between genes and diet, with the resulting potential to influence cardiovascular disease risk by dietary modification. Single-nucleotide polymorphisms in several genes have been linked to differential effects in terms of lipid metabolism; however, even a simple model of benefit and risk is difficult to interpret in terms of dietary advice to carriers of the various alleles because of conflicting interactions between different genes. The n-3 family of polyunsaturated fatty acids is underrepresented in our modern diet; much of the benefit of polyunsaturated fatty acids found in studies of various polymorphisms seems to be linked to increased n-3 polyunsaturated fatty acid intake. The nascent science of nutrigenomics faces many challenges; more and better research is needed to clarify the picture, rebut scepticism, and re-invigorate the discussion concerning genetic polymorphism and its interaction with diet.

Association of two apolipoprotein A-I gene MspI polymorphisms with lipid and blood pressure levels

INTRODUCTION

Two MspI polymorphisms in the ApoA-I gene (G-75A and C83T) have been shown to be associated with plasma HDL-cholesterol levels.

METHODS

We used a PCR-based RFLP method to determine the association of these polymorphisms with lipid parameters in 271 non-diabetic, normotriglyceridaemic Chinese subjects, of whom 104 were patients with hypertension, with 10.2% having hypercholesterolaemia and the remainder were controls.

RESULTS

As expected, the hypertensive group had higher blood pressure and indices of obesity, and a more adverse lipid profile. No differences in the ApoA-I G-75A genotype or allele frequency distributions between the controls and patients were identified. However, there was a significantly lower frequency of the CT genotype (p=0.012) and T allele (p=0.011) in the affected subjects with hypercholesterolaemia or hypertension. Similarly, blood pressure and triglyceride levels were significantly lower and HDL-cholesterol levels significantly higher in the subjects with the CT genotype compared to those with the CC genotype (p<0.05). However, the G-75A genotypes did not appear to influence the lipid or blood pressure levels. The -75A allele frequency was higher in our healthy controls than an equivalent Caucasian population (31.1% vs. 18.3%, p<0.001), whereas the 83T allele frequency was similar between the healthy Chinese and Caucasian groups.

CONCLUSION

The 83T allele may be associated with a better lipid profile and blood pressure levels in this group of Chinese subjects.

APOA1 polymorphisms are associated with variations in serum triglyceride concentrations in hypercholesterolemic individuals

Background: Apolipoprotein A-I gene (

Methods:

Results: G–75A polymorphism was associated with differences in serum concentrations of triglyceride and very low-density lipoprotein (VLDL)-cholesterol (p=0.026) in HC men. After atorvastatin treatment, women carrying the

Conclusion: Our data suggest that

Contribution of polymorphisms in the apolipoprotein AI-CIII-AIV cluster to hyperlipidaemia in patients with gout

BACKGROUND

Studies have shown that hyperuricaemia is independently related to the insulin resistance syndrome and that polymorphisms of the apolipoprotein AI-CIII-AIV cluster are also related to insulin resistance.

OBJECTIVE

To study the prevalence of polymorphisms of the apolipoprotein AI-CIII-AIV cluster in persons with gout and to determine whether these polymorphisms contribute to the pathophysiology of gout or to altered lipid concentrations.

METHODS

Plasma cholesterol, triglycerides, uric acid, VLDL, LDL, IDL, and HDL triglycerides, cholesterol, and the renal excretion of uric acid were measured in 68 patients with gout with gout and 165 healthy subjects. Polymorphisms were studied by amplification and RFLP in all subjects, using XmnI and MspI in the apolipoprotein AI gene and SstI in the apolipoprotein CIII gene.

RESULTS

The A allele at position -75 bp in the apolipoprotein AI gene was more common in patients with gout than in controls (p = 0.01). Levels of cholesterol, triglycerides, uric acid, basal glycaemia, and HDL cholesterol were higher in the patients (p<0.001). In the patients there was also an interaction between mutations at the two polymorphic loci studied in the apolipoprotein AI gene (p = 0.04). An absence of the mutation at position -75 bp of the apolipoprotein AI gene resulted in increased plasma triglyceride levels.

CONCLUSIONS

Gouty patients have an altered allelic distribution in the apolipoprotein AI-CIII-AIV cluster, which could lead to changes in levels of lipoproteins. This is not caused by a single mutation but rather by a combination of different mutations.

The apo A-I gene promoter region polymorphism determines the severity of hyperlipidemia after heart transplantation

BACKGROUND

To study whether the Apolipoprotein A-I (apo A-I) promoter region gene polymorphism produces changes in the lipid profile of heart transplant recipients.

METHODS

One hundred and three heart transplant recipients (93 men and 10 women, with a mean age of 47 +/- 13 yr) receiving triple immunosuppressive therapy were submitted to a genetic study of the apo A-I gene promoter region. Anthropometric and analytical data, including lipid profile, arterial blood pressure, were collected prior to transplantation and 3, 6, 12, and 24 months after transplantation.

RESULTS

Sixty-three subjects had the GG genotype and 40 the GA genotype. Carriers of the GA genotype had higher triglyceride levels at 6 months and 2 yr (2.50 +/- 1.20 versus 1.93 +/- 0.98 mmol/L and 2.46 +/- 1.58 versus 1.60 +/- 0.68 mmol/L, respectively, p < 0.001), and a greater rise in LDL-cholesterol at 1 yr than the GG subjects (4.57 +/- 1.16 versus 4.16 +/- 1.18 mmol/L, p < 0.05). Multiple regression analyses showed that genetic variants at the apo A-I promoter region are responsible for 11% of the variability in triglyceride levels at 6 months (p = 0.005).

CONCLUSIONS

The GA genotype of the apo A-I promoter region produces a greater rise in plasma triglyceride and LDL-cholesterol levels in heart transplant patients.

Effects of apolipoprotein A-I genetic variations on plasma apolipoprotein, serum lipoprotein and glucose levels

The present authors investigated the individual and combined associations of the apolipoprotein (apo) A-I -75 bp and +83 bp polymorphisms with plasma lipid, lipoprotein and apolipoprotein levels in 734 Caucasian men and women. The frequency of the A allele at position -75 bp (G-->A) was 0.14 in women and 0.17 in men. The frequencies for the rare M2 allele at position +83 bp and/or 84 bp (C-->T and G-->A, respectively) were 0.04 and 0.05 in women and men, respectively. In women, the A allele was associated with significantly higher levels of apo B (P = 0.016), total cholesterol (TC) (P = 0.005), low-density lipoprotein cholesterol (LDL-C) (P = 0.018) and TC:high-density lipoprotein (HDL) ratio (P = 0.026) compared to the G/G subjects. In men, no significant associations were detected between the -75 bp polymorphism and any lipid trait examined. The M2 allele for the +83 bp polymorphism was significantly associated in men with higher levels of apo A-I (P = 0.002) and TC (P = 0.046). In women, a significant effect was observed for TC (P = 0.036), with M2+/- subjects having lower levels than M2+/+ subjects. Significant linkage disequilibrium (P = 0.037) between the apo A-I -75 bp and +83 bp polymorphisms was detected. Women carrying both rare alleles (G/A M2+/-) had significantly higher TC:HDL ratios (P = 0.031) compared to the other haplotypes. In men, significant differences were observed for apo A-I (P = 0.021) and TC (P = 0.044), with carriers of the G/G M2+/- haplotype having the highest values compared to other genotype combinations. In conclusion, the -75 bp (G/A) polymorphism appears to have a significant effect on levels of apo B, plasma TC and LDL-C in women, while the +83 bp polymorphism seems to affect the apo A-I levels in men, and the plasma cholesterol levels in both genders.

Polyunsaturated fatty acids modulate the effects of the APOA1 G-A polymorphism on HDL-cholesterol concentrations in a sex-specific manner: the Framingham Study

BACKGROUND

A common G-to-A substitution in the promoter area (-75 base pairs) of the apolipoprotein A-I gene (APOA1) has been described. The A allele was shown to be associated with higher HDL-cholesterol concentrations in some studies but not in others.

OBJECTIVE

We examined whether dietary fat modulates the association between this polymorphism and HDL-cholesterol concentrations.

DESIGN

We studied a population-based sample of 755 men and 822 women from the Framingham Offspring Study.

RESULTS

The frequency of the A allele was 0.165. No significant differences were observed between G/G subjects and carriers of the A allele for any lipid variables. In multivariate linear regression models, HDL-cholesterol concentrations in women were associated with a significant interaction between polyunsaturated fatty acid (PUFA) intake as a continuous variable and APOA1 genotype (P = 0.005). By using 3 categories of PUFA intake, we found a significantly different effect of APOA1 genotype across PUFA categories in women. When PUFA intake was <4% of energy, G/G subjects had approximately 14% higher HDL-cholesterol concentrations than did carriers of the A allele (P < 0.05). Conversely, when PUFA intake was >8%, HDL-cholesterol concentrations in carriers of the A allele were 13% higher than those of G/G subjects (P < 0.05). No significant allelic difference was observed for subjects in the range of PUFA intake of 4-8% of energy. These interactions were not significant in men.

CONCLUSIONS

We found a significant gene-diet interaction associated with the APOA1 G-A polymorphism. In women carriers of the A allele, higher PUFA intakes were associated with higher HDL-cholesterol concentrations, whereas the opposite effect was observed in G/G women.

Genetic polymorphisms and lipid response to dietary changes in humans

BACKGROUND

Previous studies on the effects of genetic polymorphisms on the serum cholesterol response to dietary treatments were often inconsistent and frequently involved small numbers of subjects.

MATERIALS AND METHODS

We studied the effect of 10 genetic polymorphisms on the responses of serum cholesterol to saturated and trans fat, cholesterol and the coffee diterpene, cafestol, as measured in 26 dietary trials performed over 20 years in 405 mostly normolipidaemic subjects.

RESULTS

Apoprotein A4 360-2 allele attenuated the response of low-density lipoprotein cholesterol to dietary cholesterol, but not in women. Subjects with the cholesteryl ester transfer protein TaqIb-1 allele had -0.02 to -0.05 mmol L-1 smaller responses of high-density lipoprotein cholesterol to diet than those with the 2/2 genotype. The effects of the other eight polymorphisms on cholesterol response were either inconsistent with results in previous studies or need to be replicated in other studies.

CONCLUSIONS

Apoprotein A4360 and cholesteryl ester transfer protein TaqIb polymorphisms may affect dietary responses. However, no one single genotype was a major determinant of a subject's lipid response to diet. Therefore, knowledge of these genotypes by themselves is of little use in the identification of subjects who may or may not benefit from dietary treatment.

The genetics of serum lipid responsiveness to dietary interventions

CHD is a multifactorial disease that is associated with non-modifiable risk factors, such as age, gender and genetic background, and with modifiable risk factors, including elevated total cholesterol and LDL-cholesterol levels. Lifestyle modification should be the primary treatment for lowering cholesterol values. The modifications recommended include dietary changes, regular aerobic exercise, and normalization of body weight. The recommended dietary changes include restriction in the amount of total fat, saturated fat and cholesterol together with an increase in the consumption of complex carbohydrate and dietary fibre, especially water-soluble fibre. However, nutrition scientists continue to question the value of these universal concepts and the public health benefits of low-fat diets, and an intense debate has been conducted in the literature on whether to focus on reduction of total fat or to aim efforts primarily towards reducing the consumption of saturated and trans fats. Moreover, it is well known that there is a striking variability between subjects in the response of serum cholesterol to diet. Multiple studies have examined the gene-diet interactions in the response of plasma lipid concentrations to changes in dietary fat and/or cholesterol. These studies have focused on candidate genes known to play key roles in lipoprotein metabolism. Among the gene loci examined, APOE has been the most studied, and the current evidence suggests that this locus might be responsible for some of the inter-individual variability in dietary response. Other loci, including APOA4, APOA1, APOB, APOC3, LPL and CETP have also been found to account for some of the variability in the fasting and fed states.

Influence of genetic variation at the apo A-I gene locus on lipid levels and response to diet in familial hypercholesterolemia

We have examined the apo AI - 75 (G/A) and apo AI + 83(MspI +/-) polymorphisms at the APOA1 gene locus for associations with plasma lipid levels and response to an NCEP-I diet in 69 (44 women, 25 men) heterozygotes for familial hypercholesterolemia (FH). Subjects were studied at baseline (after consuming for one month a diet with 35%, fat, 10% saturated, and 300 mg/day cholesterol) and after 3 months of an NCEP-I diet. No gender-related differences for any of the lipid variables examined were found and the data were analyzed for men and women combined. For the apo AI - 75 (G/A) polymorphism, there were 51 G/G and 18 G/A subjects. At baseline, G/A subjects showed significantly lower total cholesterol (p = 0.0036), and LDL-C (p = 0.0023), and apo B (p = 0.0209), than G/G individuals, but no differences were found for HDL-C, triglycerides and VLDL-C values. Following the NCEP-I diet these genotype-related differences remained significant for total and LDL-C. The MspI (-) allele at the apo AI + 83 polymorphism was detected in the heterozygous state in five subjects and its presence was not associated with altered baseline lipids nor with dietary response to the NCEP-I diet. Our results suggest that FH subjects carrying the A allele at the apoAI - 75 (G/A) polymorphism have significantly lower total and LDL-C and apo B baseline levels but respond to a low-fat diet with similar reductions in total and LDL-C when compared with homozygotes for the G allele at this polymorphic site.

Human apolipoprotein A-I gene promoter mutation influences plasma low density lipoprotein cholesterol response to dietary fat saturation

Previous studies have shown that the A to G transition occurring at position -75 bp upstream of the transcriptional start site in the human apolipoprotein A-I gene may affect plasma high density lipoprotein cholesterol (HDL-C) levels and low density lipoprotein cholesterol (LDL-C) response to changes in amount of dietary fat. We have examined the response to dietary fat saturation as a function of this mutation in 50 men and women. Subjects were first fed a saturated (SAT) fat diet (35% fat, 17% SAT) for 28 days, followed by a diet rich in monounsaturated fatty (MUFA) acids (35% fat, 22% MUFA) for 35 days and a diet rich in polyunsaturated (PUFA) fat (35% fat, 13% PUFA) for 35 days. All meals were prepared and consumed at the study sites. Lipoproteins were measured at the end of each diet period. The allele frequency for the A allele was 0.13. Subjects carrying the A allele had higher plasma cholesterol, LDL-C and triglyceride levels than those homozygotes for the G allele. As compared to the SAT diet, a PUFA diet induced significantly greater plasma total (P = 0.003) and LDL-C decreases (P = 0.001) in G/A women (-1.62 and -1.32 mmol/l, respectively) than in G/G subjects (-0.87 and -0.74 mmol/l for plasma and LDL-C, respectively). Multiple regression analysis demonstrated that in women, the variability in LDL-C response from a diet rich in SAT fat to a diet rich in PUFA was primarily due to LDL-C levels (during the SAT phase), accounting for 55.1% of the variance, waist to hip ratio (W/H; 11.4%) and the G/A polymorphism (10%). Whereas in men the major determinant of this response was smoking (21.4%). In conclusion, the G/A polymorphism appears to have a small but significant effect on plasma LDL-C responsiveness to changes in dietary fat saturation specially in women.

Response to dietary fat and cholesterol and genetic polymorphisms

1. We examined common polymorphisms in the genes encoding the LDL receptor, lipoprotein lipase, apoAI, apoB, apoAIV and cholesteryl ester transfer protein and related them to changes in LDL and HDL cholesterol after high fat/high cholesterol diets. 2. The only significant association was seen with the apoIV polymorphism, which leads to a structural change in the protein. The response to fat and cholesterol in subjects with at least one apoAIV 2 allele was only 30% of that seen in subjects with the common apoIV 1 allele (P < 0.01), accounting for 6-7% of the variance in response. This confirms the results of two previous studies in which dietary cholesterol intake was changed. 3. No association were seen with polymorphisms of the other five genes examined.