The apolipoprotein B signal peptide insertion/deletion polymorphism is not associated with myocardial infarction in Norway

Associations of the APOB rs693 and rs17240441 polymorphisms with plasma APOB and lipid levels: a meta-analysis

BACKGROUND

The associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive. This meta-analysis aimed to clarify the associations of the rs693 and rs17240441 polymorphisms with fasting APOB and lipid levels.

METHODS

Sixty-one studies (50,018 subjects) and 23 studies (8425 subjects) were respectively identified for the rs693 and rs17240441 polymorphisms by searching in PubMed, Google Scholar, Web of Science, Cochrane Library, Wanfang, VIP and CNKI databases. The following information was collected for each study: first author, age, gender, ethnicity, health condition, sample size, genotyping, lipid assay method, mean and standard deviation or standard error of APOB and lipid variables by genotypes. A dominant model was used for this meta-analysis.

RESULTS

The carriers of the rs693 variant allele (T) had higher levels of APOB [standardized mean difference (SMD) = 0.26, 95% confidence interval (CI) = 0.16-0.36, P < 0.01], triglycerides (TG) (SMD = 0.12, 95% CI = 0.05-0.20, P < 0.01), total cholesterol (TC) (SMD = 0.24, 95% CI = 0.17-0.30, P < 0.01) and low-density lipoprotein cholesterol (LDL-C) (SMD = 0.22, 95% CI = 0.14-0.30, P < 0.01), and lower levels of high-density lipoprotein cholesterol (HDL-C) (SMD = -0.06, 95% CI = -0.11-0.01, P = 0.01) than the non-carriers. The carriers of the rs17240441 deletion allele had higher levels of APOB (SMD = 0.13, 95% CI = 0.06-0.20, P < 0.01), TC (SMD = 0.17, 95% CI = 0.07-0.26, P < 0.01) and LDL-C (SMD = 0.15, 95% CI = 0.07-0.23, P < 0.01) than the non-carriers.

CONCLUSIONS

The rs693 polymorphism is significantly associated with higher levels of APOB, TG, TC and LDL-C, and lower levels of HDL-C. The rs17240441 polymorphism is significantly associated with higher levels of APOB, TC and LDL-C. Further studies are needed to elucidate the underlying mechanisms.

Association between apolipoprotein B gene polymorphisms and the risk of coronary heart disease (CHD): an update meta-analysis

OBJECTIVE

Polymorphisms in the apolipoprotein B (apoB) gene have been reported to be associated with coronary heart disease (CHD). However, the results on this topic are conflicting. The present study aims to derive a more precise estimation of the relationship between CHD and apoB genetic polymorphisms by meta-analysis.

METHODS

We identified a total of 54 studies involving 7236, 10,912, and 14,102 individuals, respectively, for EcoRI, XbaI, and SpIns/Del polymorphisms by searching in PubMed, Web of Science, Google Scholar, the Cochrane Library, Wanfang Data, SinoMed, and CNKI. We utilized RevMan 5.0 software to perform the meta-analyses.

RESULTS

A significant statistical association between apoB EcoRI polymorphism and CHD was observed under an allelic (p = 0.001, odds ratio (OR) = 1.33, 95% confidence interval (CI) = 1.12-1.57), dominant (p = 0.005, OR = 1.22, 95% CI = 1.06-1.40), and recessive (p = 0.04, OR = 1.33, 95% CI = 1.01-1.74) model. We also found similar association of apoB SpIns/Del polymorphism with CHD. However, we did not find association between apoB XbaI polymorphism and CHD.

CONCLUSION

The current meta-analysis found an association of EcoRI polymorphism and SpIns/Del polymorphism with an increased risk of CHD. No significant association between apoB XbaI polymorphism and CHD we observed in the present study.

ApoB gene SpIns/Del, XbaI polymorphisms and myocardial infarction: a meta-analysis of 7169 participants

BACKGROUND

Apolipoprotein B (ApoB) gene signal peptide insertion/deletion (SpIns/Del, I/D) and XbaI polymorphisms have been associated with susceptibility to myocardial infarction (MI). However, the results of studies on this association are still controversial.

OBJECTIVE AND METHODS

This study explored reports published from 1986 to 2008 regarding the association of ApoB gene SpIns/Del and XbaI polymorphisms with MI. A meta-analysis including 7169 participants from 19 individual studies was performed. The pooled odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were evaluated by fixed-effect or random-effect models.

RESULTS

A significant relationship between ApoB SpIns/Del gene polymorphism and MI was found under allelic (OR: 1.270, 95% CI: 1.090-1.480, P = 0.002), recessive (OR: 1.360, 95% CI: 1.130-1.630, P = 0.0009), dominant (OR: 1.091, 95% CI: 1.037-1.146, P = 0.001), homozygous (OR: 1.610, 95% CI: 1.330-1.950, P <0.00001) and heterozygous (OR: 1.081, 95% CI: 1.020-1.146, P = 0.009) genetic models. A marginal relationship between ApoB XbaI polymorphism and MI was found under a dominant genetic model (OR: 1.083, 95% CI: 1.004-1.168, P = 0.039). No significant association was detected under other genetic models (P >0.05). However, in the non-European subgroup analysis, increased MI risk emerged under all genetic models (P <0.05).

CONCLUSION

ApoB SpIns/Del gene polymorphism was positively associated with increased MI risk. D allele and DD genotype carriers might be predisposed to MI susceptibility. The ApoB XbaI gene polymorphism locus had a significant positive association with increased MI risk only in the non-European population. T allele and TT genotype carriers might be susceptible to MI in the non-European population. On the contrary, the ApoB gene XbaI restriction fragment length polymorphism was not associated with increased MI risk in the entire population, particularly in the European population.

The roles of genetic polymorphisms and human immunodeficiency virus infection in lipid metabolism

Dyslipidemia has been frequently observed among individuals infected with human immunodeficiency virus type 1 (HIV-1), and factors related to HIV-1, the host, and antiretroviral therapy (ART) are involved in this phenomenon. This study reviews the roles of genetic polymorphisms, HIV-1 infection, and highly active antiretroviral therapy (HAART) in lipid metabolism. Lipid abnormalities can vary according to the HAART regimen, such as those with protease inhibitors (PIs). However, genetic factors may also be involved in dyslipidemia because not all patients receiving the same HAART regimen and with comparable demographic, virological, and immunological characteristics develop variations in the lipid profile. Polymorphisms in a large number of genes are involved in the synthesis of structural proteins, and enzymes related to lipid metabolism account for variations in the lipid profile of each individual. As some genetic polymorphisms may cause dyslipidemia, these allele variants should be investigated in HIV-1-infected patients to identify individuals with an increased risk of developing dyslipidemia during treatment with HAART, particularly during therapy with PIs. This knowledge may guide individualized treatment decisions and lead to the development of new therapeutic targets for the treatment of dyslipidemia in these patients.

5' ins/del and 3' VNTR polymorphisms in the apolipoprotein B gene in relation to lipids and coronary artery disease

BACKGROUND

Studies that considered apolipoprotein B (APOB) gene polymorphisms as risk factors for coronary artery disease (CAD) have reported conflicting results. We sought to analyze the association between 5' ins/del and 3' VNTR polymorphisms of APOB, lipid parameters and CAD risk.

METHODS

We recruited 251 patients with CAD, documented by coronary angiography, and 94 controls. Genotyping was performed by PCR. Lipids and apolipoproteins were measured.

RESULTS

5' ins/del (ins/ins, ins/del, del/del) and 3' VNTR (LL, SS, LS) polymorphism frequencies were significantly (p<0.05) different between controls and CAD patients. LL and del/del were significantly associated with higher levels of apolipoprotein B (apoB), total cholesterol/high-density lipoprotein cholesterol ratio and apoB/apoA-I ratio (p<0.05) and with increased risk of CAD. The odds ratio for significant coronary stenosis associated with del/del was 3.2 (95% CI 1.6-36.42) (p=0.032) and with LL was 2.2 (95% CI 1.1-5.1) (p=0.042).

CONCLUSIONS

The two polymorphisms exert an impact on lipid levels and contribute to the susceptibility to the development of CAD.

Haplotype analysis of signal peptide (insertion/deletion) and XbaI polymorphisms of the APOB gene in gallbladder cancer

PURPOSE

The incidence of gallbladder cancer (GBC) is usually paralleled by the prevalence of gallstone disease, and genes of cholesterol metabolism have been implicated in gallstone disease. The XbaI and insertion/deletion (ins/del) polymorphism of Apolipoprotein B (APOB) appears to influence cholesterol homoeostasis and possibly risk for gallstone disease. We examined the effect of these polymorphisms individually as well as their haplotypes on GBC and gallstone patients in North Indian population.

METHODS

The study comprises 123 consecutive cases of proven GBC, 172 cases of gallstone and 232 healthy subjects of similar age and sex. The genomic DNA was extracted from peripheral blood leucocytes and genotyping was performed using polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism.

RESULTS

In a case-control study, APOB XbaI and ins/del polymorphisms were not significantly associated with risk of GBC. Using the expectation maximization algorithm, four haplotypes were obtained, and haplotype X(+),D was found to be significantly higher in GBC patients without stone in comparison with healthy subjects [odds ratio (OR) 2.9, 95% confidence interval 1.2-6.6 P=0.012].

CONCLUSIONS

The X(+),D haplotype of APOB is associated with increased risk for development of GBC and the risk is not modified in the presence of gallstones.

Apolipoprotein B signal peptide polymorphism and plasma LDL-cholesterol response to low-calorie diet

OBJECTIVE

To assess the effect of the apolipoprotein B Ins/Del signal peptide. Polymorphism on plasma lipid levels in overweight subjects before and after a low-calorie diet.

DESIGN

Diet intervention study (25% reduction in energy intake during 2.5 months) in relation to genetic factors.

SUBJECTS

A total of 231 unrelated patients (146 women/85 men) recruited on the basis of body mass index (BMI)> or =25 kg/m(2).

MEASUREMENTS

BMI, waist to hip ratio, blood lipids and lipoproteins, at entry and after 2.5 months, determination of apo B Ins/Del genotypes.

RESULTS

On spontaneous diet, subjects carrying the Del allele had higher LDL-cholesterol (Del/Del: 3.97+/-0.62 mmol/l; Ins/Del: 3.87+/-1.01 mmol/l; Ins/Ins: 3.61+/-0.88 mmol/l) (P=0.038). When submitted to low-calorie diet, subjects with Del/Del genotypes reduced their LDL-cholesterol (-16.8%) more than subjects with Ins/Del or Ins/Ins (-4.7% and +0.9%, respectively) (P=0.001).

CONCLUSION

In overweight or obese people, the response of plasma LDL-cholesterol levels to low-calorie diet is modulated by genetic variation at the apo B locus. Overweight subjects with the Del allele of the apo B signal peptide polymorphism are predisposed to high LDL cholesterol levels but their LDL cholesterol responds well to diet. These results demonstrate the importance of the interaction between genes and nutritional environment in the determination of the lipid levels.

Molecular variation at the apolipoprotein B gene locus in relation to lipids and cardiovascular disease: a systematic meta-analysis

Apolipoprotein B (apoB) is the sole protein component of low-density lipoprotein (LDL) and is thought to play an important role in atherogenesis. We performed a meta-analysis of the associations between the three most frequently investigated polymorphisms (XbaI, signal peptide insertion/deletion, EcoRI) in the apolipoprotein B (APOB) gene, lipid parameters, and the risk of ischemic heart disease (IHD). We restricted our analysis to Caucasians. Homozygotes for the XbaI X+ allele had significantly elevated levels of LDL cholesterol (LDL-C) and apoB, but a decreased risk (OR=0.80; 95%CI: 0.66-0.96) of IHD. Homozygosity for the signal peptide deletion allele was associated with similarly increased levels of LDL-C and apoB, and with an increased risk of IHD (OR=1.30; 95%CI: 1.08-1.58). Subjects homozygous for the rare EcoRI allele had significantly decreased levels of total and LDL cholesterol, but unaltered risk of IHD. We conclude that all three polymorphic apoB sites are associated with altered lipid levels, but not necessarily with a consistently altered risk of IHD. These data suggest that the relationship between apoB levels, hypercholesterolemia and IHD risk cannot have a simple molecular basis in the apoB gene.

Interaction between SREBP-1a and APOB polymorphisms influences total and low-density lipoprotein cholesterol levels in patients with coronary artery disease

In this study, we examined the insertion/deletion (Ins/Del) and XbaI polymorphisms of the apolipoprotein B (APOB) gene and the -36delG polymorphism in the sterol regulatory element binding protein-1a (SREBP-1a) gene in 298 patients with non-diabetic angiographically assessed coronary artery disease (CAD), and 188 healthy controls, from a Brazilian population of European descent. Del/X+ haplotype carriers had higher levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in patients (TC, p = 0.05; LDL-C, p = 0.049) and controls (TC, p = 0.004; LDL-C, p = 0.013). No association was detected between the SREBP-1a-36delG polymorphism and lipid levels, but a significant interaction effect between APOB and SREBP-1a polymorphisms was observed in the patient sample on TC (p = 0.005) and on LDL-C (p = 0.019) levels. Carriers of the APOB Del/X+ haplotype and SREBP-1a G-G- genotype showed the highest levels of these lipid parameters. This effect of interaction was not observed in the control sample. Despite the associations with lipids, these polymorphisms were not associated with CAD risk or severity in this sample.

Genetic determination of plasma lipids and insulin in the Czech population

OBJECTIVES

To evaluate the association between plasma lipids and insulin and variation in the genes for apolipoproteins (APO) E (CfoI), B (insertion/deletion), C1 (HpaI), and C3 (C-482T, C3238G) in a population-based Czech Slavonic study.

DESIGN AND METHODS

In 131 men and 154 women, polymorphisms were investigated using PCR. In the same subjects plasma lipid levels and insulin were measured.

RESULTS

In the women, carriers of the e4 allele had higher apoB (p = 0.03) and triglyceride (p = 0.03) compared to e3 homozygotes, whereas in the men, the effect of the e4 allele was seen on total cholesterol (p = 0.02), LDL cholesterol (p = 0.003) and apoB (p = 0.001). Compared with SP27 (insertion) homozygotes of the APOB polymorphism, women SP24 (deletion) homozygotes had higher levels of total (p = 0.003) and LDL cholesterol (p = 0.007) and apoB (p = 0.05). No significant effect was seen in the men. Women homozygous for the APOC3 -482T allele had higher insulin levels than -482C homozygotes (p = 0.03). Men homozygous for APOC3 -482T allele have the highest plasma triglyceride level (p = 0.02). The APOC1 polymorphism exhibited no significant effect on any of the parameters studied.

CONCLUSIONS

In this sample, variation at the APOE, APOB and APOC3 genes play a role in determining plasma levels of insulin and lipids, and emphasize the importance of gender-associated effects in the genetic determinations.

A common apolipoprotein B signal peptide polymorphism modifies the relation between plasma non-esterified fatty acids and triglyceride concentration in men

Insulin and non-esterified fatty acids (NEFA) are important regulators of triglyceride metabolism. The relations between these compounds and the effect of a common 3 amino acid deletion in the apolipoprotein B (ApoB) signal peptide (SP) following an oral glucose challenge have been investigated. The frequency of the shorter SP-24 allele was 32% (95% C.I. 29.5-36.5) in 725 subjects undergoing an oral glucose tolerance test (OGTT). Fasting plasma triglyceride concentration was positively correlated with fasting plasma insulin concentration and negatively with the degree of plasma NEFA suppression following the glucose challenge. Linear regression analysis showed the relation between triglyceride concentration and NEFA suppression, but not the relation between triglyceride concentration and fasting insulin, to be altered by the SP polymorphism in men but not in women. The strength of the association was dependent on the number of SP-24 alleles, with SP-24 homozygotes showing the greatest dependence (men P=0.031, women P=0. 914). It was proposed that the complex regulation of very low density lipoprotein (VLDL) output by NEFA and by insulin may explain, at least in part, the conflicting reports concerning the presence of the ApoB SP polymorphism, fasting serum lipids and ischaemic heart disease (IHD).

Single effects of apolipoprotein B, (a), and E polymorphisms and interaction between plasminogen activator inhibitor-1 and apolipoprotein(a) genotypes and the risk of coronary artery disease in Czech male caucasians

To evaluate whether polymorphisms in genes whose products are involved in lipid metabolism and fibrinolysis alter the risk of coronary artery disease (CAD), allele frequencies of four genetic polymorphisms were ascertained by PCR-based methods in 175 Czech male patients with coronary artery disease and in 222 Czech men with no symptoms of CAD. The following polymorphisms were studied: apolipoprotein B (apo B) signal peptide insertion/deletion polymorphism, 5' apolipoprotein(a) [apo(a)] TTTTA repeat polymorphism, apolipoprotein E (apo E) varepsilon2, varepsilon3, varepsilon4 polymorphism, and plasminogen activator inhibitor-1 (PAI-1) 4G/5G promoter polymorphism. Apo B and apo(a) allele frequencies differed significantly between the CAD and the control groups (P<0.01 each), with higher frequencies of apo B deletion and apo(a) shorter repeat alleles in the CAD group. We did not observe any differences in allele frequencies of either PAI-1 or apo E polymorphisms but the genotype frequencies of apo E were slightly different between the two groups (P<0.05). In addition, we observed a gene-gene interaction between the PAI-1 and apo(a) polymorphisms with respect to the risk of CAD. None of the polymorphisms studied were associated with the severity of CAD or a history of myocardial infarction. Our findings support the idea that several polymorphisms in apolipoprotein genes may by themselves and/or in interaction with other polymorphisms contribute to risk factors for CAD in men.

Variation of apolipoprotein B as a possible cause of decreased low density lipoprotein clearance and hypercholesterolemia

The fractional catabolic rate (FCR) for low density lipoprotein (LDL) apolipoprotein B (apo B) was studied to explore the variations in apo B as a possible cause of hypercholesterolemia. The FCR of radioiodine labelled autologous LDL and homologous LDL isolated from a normocholesterolemic subject were compared in forty-nine type II hypercholesterolemic males and females with the mean plasma concentration of total cholesterol of 7.78 mmol/l, LDL-cholesterol 5.41 mmol/l and triglycerides 2.09 mmol/l. In most patients the autologous LDL was catabolized at an equal rate and sometimes even faster than the homologous LDL. However, twelve out of forty-nine patients catabolized homologous LDL 0.8-19.3% faster than autologous LDL and several apo B polymorphisms were determined. No apo B-3500 or apo B-3531 mutations were detected. Patients with XbaI -/- (absence of cutting site) had lower total, IDL and LDL cholesterol and LDL apoB than the other genotypes. Patients with EcoRI +/+ (presence of cutting site) had higher total, VLDL and LDL cholesterol and slower FCR for autologous LDL, and their VLDL was richer in cholesterol than that of patients with the EcoRI +/-. The MspI and ins/del polymorphisms were not associated with variations in the measured parameters. The apo E 4 was associated with higher VLDL and IDL cholesterol, higher triglycerides and LDL apo B than E 3/3. Overall, the determined apo B polymorphisms were not related to the slow clearance of autologous LDL among the 12 patients, in whom autologous LDL was cleared at a slower rate than homologous LDL. In conclusion, hypercholesterolemia can be due to particle-related slow clearance of LDL in some patients. However, this is not a common cause of hypercholesterolemia.

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.

Association of the insertion/deletion gene polymorphism of the apolipoprotein B signal peptide with myocardial infarction

The Del allele of the apolipoprotein B (apoB) signal peptide (SP) insertion/deletion (Ins/Del) polymorphism has been shown to be associated with elevated plasma levels of apoB, cholesterol and low density lipoprotein. It was the aim of the present study to analyse the relation of this gene variation to the risk of coronary artery disease (CAD) and of myocardial infarction (MI) in a population of 2259 male Caucasians, whose coronary anatomy was defined by means of coronary angiography. ApoB SP DelDel genotypes had significantly higher apoB plasma concentrations than InsIns homozygotes (P = 0.0001) and InsDel heterozygotes (P = 0.002); however, the apoB plasma levels of InsIns and InsDel genotypes were essentially the same (P = 0.54). Similar observations were made with respect to ApoB SP genotype-dependent cholesterol plasma concentrations. Since the apoB plasma level was not only associated with the apoB SP Ins/Del gene variation but also to the extent of coronary artery disease (P <0.0001), individuals with an InsIns genotype and without CAD had the lowest and subjects with a DelDel genotype and triple vessel disease the highest apoB plasma levels (P <0.0001). An association of the apoB SP Ins/Del gene variation with CAD was not detected, neither in the total population nor in low risk groups. In contrast, the gene variation was associated with MI (P <0.05). An Odds ratio of 1.18 (95% CI, 1.01-1.39) associated with the Del allele was detected in the total sample (P <0.02). In a subpopulation of individuals with low plasma triglyceride levels ( <154 mg/dl; mean value) and an DD genotype of the angiotensin I-converting enzyme insertion/deletion gene polymorphism an Odds ratio of 2.01 (1.42-3.05) was calculated (P <0.001). The present study presents evidence for a statistically significant difference in the development of MI between genotype classes of the apoB SP Ins/Del gene polymorphism.

Study of apoB gene signal peptide insertion/deletion polymorphism in a healthy Serbian population: no association with serum lipid levels

The apolipoprotein B (apoB) signal peptide polymorphism was studied in unrelated healthy individuals. A total of 232 women and 222 men were analyzed separately. The relative frequencies of Del allele in women and men were 0.42 and 0.37, respectively. More heterozygous individuals were detected in comparison with other populations, using a modified silver staining method on polyacrylamide gel for visualization of Ins and Del alleles. There was no statistically significant difference in mean lipid levels adjusted for age, BMI, smoking habit and blood pressure between the three Ins/Del genotypes in both samples (ANOVA). Therefore, no differences were shown in the genotype frequency distribution throughout the lipid quartiles.

Frequencies of five genetic polymorphisms in coronarographed patients and effects on lipid levels in a supposedly healthy population

Allele frequencies of genetic polymorphisms were compared between supposedly healthy subjects and angiographically proven coronary artery disease patients. The polymorphic candidate loci investigated were the apolipoprotein (apo) B signal peptide and XbaI polymorphism, the apo E polymorphism and two polymorphism of lipoprotein lipase (LPL) gene: Hind/III and PvuII. Apo B signal peptide and HindIII/LPL polymorphisms showed significant differences in allele partition between cases and controls; the rare alleles of both polymorphisms were less frequent (p < 0.05) in cases. We looked for associations between the polymorphisms and lipid concentration variability in a supposedly healthy population (145 men and 144 women). Apo B signal peptide, apo E and PvuII/LPL polymorphisms seem to influence some lipid metabolism parameters significantly. Apo AI and LpCIII levels were significantly different among apo B signal peptide genotypes: Del homozygotes had the highest concentrations of both variables. The epsilon 4 allele of apo E polymorphism was associated with increased concentrations of total cholesterol, LDL cholesterol and apo B. Increased LpAI:AII levels observed in E3 homozygotes (p < 0.01) have not previously been reported. LpAI:AII concentration was also influenced by PvuII/LPL polymorphisms.

Genotyping apolipoprotein B signal peptide insertion/deletion: a comparison of three methods

Three different ways of detecting insertion/deletion (Ins/Del) genotypes of the apolipoprotein B gene encoding signal peptide were compared. Unequal quantities of the two alleles were observed in 50 Serbian subjects. The low abundance allele was clearly visible only when a modified method of silver staining for polyacrylamide gels was used. This method is more reliable for Ins/Del polymorphism genotyping, avoiding misclassifications by conventional ethidium bromide staining of both agarose and polyacrylamide gels.