Detection of variability in apo(a) gene transcription regulatory sequences using the DGGE method

Lipoprotein(a) beyond the kringle IV repeat polymorphism: The complexity of genetic variation in the LPA gene

High lipoprotein(a) [Lp(a)] concentrations are one of the most important genetically determined risk factors for cardiovascular disease. Lp(a) concentrations are an enigmatic trait largely controlled by one single gene (LPA) that contains a complex interplay of several genetic elements with many surprising effects discussed in this review. A hypervariable coding copy number variation (the kringle IV type-2 repeat, KIV-2) generates >40 apolipoprotein(a) protein isoforms and determines the median Lp(a) concentrations. Carriers of small isoforms with up to 22 kringle IV domains have median Lp(a) concentrations up to 5 times higher than those with large isoforms (>22 kringle IV domains). The effect of the apo(a) isoforms are, however, modified by many functional single nucleotide polymorphisms (SNPs) distributed over the complete range of allele frequencies (<0.1% to >20%) with very pronounced effects on Lp(a) concentrations. A complex interaction is present between the apo (a) isoforms and LPA SNPs, with isoforms partially masking the effect of functional SNPs and, vice versa, SNPs lowering the Lp(a) concentrations of affected isoforms. This picture is further complicated by SNP-SNP interactions, a poorly understood role of other polymorphisms such as short tandem repeats and linkage structures that are poorly captured by common R² values. A further layer of complexity derives from recent findings that several functional SNPs are located in the KIV-2 repeat and are thus not accessible to conventional sequencing and genotyping technologies. A critical impact of the ancestry on correlation structures and baseline Lp(a) values becomes increasingly evident.

This review provides a comprehensive overview on the complex genetic architecture of the Lp(a) concentrations in plasma, a field that has made tremendous progress with the introduction of new technologies. Understanding the genetics of Lp(a) might be a key to many mysteries of Lp(a) and booster new ideas on the metabolism of Lp(a) and possible interventional targets.

Abrupt opium discontinuation has no significant triggering effect on acute myocardial infarction

OBJECTIVES

A deleterious effect of withdrawal symptoms due to abrupt discontinuation of opium on the cardiovascular system is one of the recent interesting topics in the cardiovascular field. The current study hypothesized that the withdrawal syndrome due to discontinuing opium might be an important trigger for the appearance of acute myocardial infarction.

METHODS AND RESULTS

Eighty-one opium-addicted individuals who were candidates for cardiovascular clinical evaluation and consecutively hospitalized in the coronary care unit (CCU) ward of Shafa Hospital in Kerman between January and July 2009 were included in the study and categorized in the case group, including patients experiencing withdrawal symptoms within 6-12 h after the reduced or discontinued use of opium according to the Diagnostic and Statistical Manual of Mental Disorders-revised IV version (DSM-IV-R) criteria for opium dependence and withdrawal, and the control group, without opium withdrawal symptoms. The appearance of acute myocardial infarction was compared between the two groups using multivariable regression models. Acute myocardial infarction occurred in 50.0% of those with withdrawal symptoms and in 45.1% of patients without evidence of opium withdrawal (P = 0.669). Multivariable analysis showed that opium withdrawal symptoms were not a trigger for acute myocardial infarction adjusting for demographic characteristics, marital status, education level and common coronary artery disease risk profiles [odds ratio (OR) = 0.920, 95% confidence interval (CI) = 0.350-2.419, P = 0.866]. Also, daily dose of opium before reducing or discontinuing use did not predict the appearance of myocardial infarction in the presence of confounder variables (OR = 0.975, 95% CI = 0.832-1.143, P = 0.755).

CONCLUSION

Withdrawal syndrome due to abrupt discontinuation of opium does not have a triggering role for appearance of acute myocardial infarction.

Screening and therapeutic management of lipoprotein(a) excess: review of the epidemiological evidence, guidelines and recommendations

Lipoprotein(a) (Lp(a)) is a low density lipoprotein-like particle in which apolipoprotein B100 is covalently linked to the unique apolipoprotein(a). There is a mounting body of evidence suggesting a role of Lp(a) in the development and progression of several vascular diseases, such as coronary heart disease, ischemic stroke, abdominal aortic aneurysm and venous thromboembolism, so that prominent scientific societies have recently endorsed guidelines and recommendations that increasingly encourage the screening and the therapeutic management of Lp(a) excess. In this article, we review the epidemiologic evidence, guidelines and recommendations concerning the relationship between increased plasma Lp(a) levels and risk of cardiovascular disease or venous thromboembolism by systematically retrieving the most relevant articles from electronic databases. Although uncertainty still remains regarding the opportunity to screen for hyperlipoproteinemia(a), it seems inopportune as yet to measure plasma Lp(a) levels in asymptomatic persons, while its measurement might be of clinical significance in selected categories of patients at intermediate or high cardiovascular risk. The measurement of Lp(a) should be performed by using immunometric, harmonized and size-insensitive techniques and results reported in total lipoprotein mass rather than in traditional units. It is uncertain if Lp(a) genotyping or phenotyping add any additional information for the cardiovascular disease risk stratification. Although the optimal therapeutic management of Lp(a) excess is still controversial, a general agreement exists that very high Lp(a) levels should be lowered in patients with multiple cardiovascular risk factors, preferably with nicotinic acid therapy (e.g., 1.0-3.0 g/day).

Effect of opium addiction on new and traditional cardiovascular risk factors: do duration of addiction and route of administration matter?

Background

There is a belief among some society that opium has a number of beneficial effects on cardiovascular disease. The aim of the present investigation as a cross-sectional study was to assess this hypothesis. Several biochemical factors (Fasting blood sugar, Cholesterol, Triglyceride, LDL-Cholesterol, HDL-Cholesterol, HbA1C, CRP, Fibrinogen, Factor VII, SGOT, SGPT, Lpa, apo A and apo B were evaluated in opium-addicted men (case) against non opium-addicted men(control). Three hundred and sixty opium-addicted men were divided into three groups according to the route of administration (Orally, Vafour and Sikh-Sang) and each group was divided into four subgroups according to the duration of addiction (5 months, 1 year, 2 years and 5 years). Blood morphine concentration was measured by ELISA method.

Results

The results show that morphine concentration was significantly higher in orally administration. In all routes, there was a direct correlation between blood morphine concentration and period of addiction. Regardless to the period and route of administration, the level of HbA1C, CRP, factor VII, Fibrinogen, apo B, Lpa, SGOT, and SGPT were significantly higher in the case subjects as compared with controls and HDL-Cholesterol and apo a were significantly lower in the case subjects.

Conclusion

This study demonstrated the deleterious effects of opium on some traditional and new cardiovascular disease risk factors. These deleterious effects are related to the period of addiction and their levels are significantly increased after 2 years of addiction. Route of administration impresses cardiovascular risk factors and "Sikh-Sang" showed the worst effect.

Fish intake and LPA 93C>T polymorphism: gene-environment interaction in modulating lipoprotein (a) concentrations

High plasma lipoprotein (a) [Lp(a)] concentrations are an independent risk factor for atherosclerotic diseases. To date, no effective intervention strategies on reducing Lp(a) concentrations have been reported. The aim of the study was to evaluate the possible modulation of two polymorphisms of LPA gene (LPA 93C>T and LPA 121G>A) and nutritional habits on Lp(a) concentrations. We studied 647 healthy Italian subjects (260 M; 387 F) with a median age of 48 years (range: 19-78) enrolled in an epidemiological study conducted in Florence, Italy. A linear regression analysis showed a significant negative influence of fish intake (beta=-0.174+/-0.084; p=0.04) on Lp(a) concentrations, after adjustment for smoking habit, C-reactive protein serum concentrations, dietary habits and LDL-cholesterol concentrations. With regard to LPA polymorphisms, LPA 93C>T polymorphism resulted to significantly affect Lp(a) circulating concentrations in a dose-dependent manner, with lower concentrations shown by subjects carrying the T rare allele, whereas no significant influence of LPA 121G>A polymorphism on Lp(a) concentrations was observed. Moreover, by analyzing the possible interplay between LPA 93C>T and dietary fish intake, a significant interaction between these two determinants in lowering Lp(a) concentrations was reported. In addition, lower Lp(a) concentrations were observed in subjects carrying the T allele of the LPA 93C>T polymorphism and consuming a high intake of fish with respect to those being in the highest tertile of fish consumption but homozygotes for the common allele of the polymorphism. In conclusion, this study reported a significant interaction of daily fish intake and LPA 93C>T polymorphism in decreasing Lp(a) concentrations.

Variability in apo(a) gene regulatory sequences, compound genotypes, and association with Lp(a) plasma levels

OBJECTIVES

Lipoprotein(a) is an independent risk factor of atherosclerosis.

DESIGN AND METHODS

We assigned frequencies of six polymorphic sites from apo(a) gene transcription control regions, linkage disequilibrium, and 5-polymorphic compound genotypes association with Lp(a) levels.

RESULTS

Significant linkage disequilibrium between polymorphic sites was detected. Compound genotypes were significantly associated with Lp(a) levels (P<0.0001). Major 5-polymorphic genotypes were distributed in a broad range of concentrations.

CONCLUSIONS

Major 5-polymorphic compound genotypes are not associated with restricted range of Lp(a) levels.