Relative contributions of genes, environment, and interactions to blood lipid concentrations in a general adult population

Appropriateness of Dyslipidemia Management Strategies in Post-Acute Coronary Syndrome: A 2023 Update

It has been consistently demonstrated that circulating lipids and particularly low-density lipoprotein cholesterol (LDL-C) play a significant role in the development of coronary artery disease (CAD). Several trials have been focused on the reduction of LDL-C values in order to interfere with atherothrombotic progression. Importantly, for patients who experience acute coronary syndrome (ACS), there is a 20% likelihood of cardiovascular (CV) event recurrence within the two years following the index event. Moreover, the mortality within five years remains considerable, ranging between 19 and 22%. According to the latest guidelines, one of the main goals to achieve in ACS is an early improvement of the lipid profile. The evidence-based lipid pharmacological strategy after ACS has recently been enhanced. Although novel lipid-lowering drugs have different targets, the result is always the overexpression of LDL receptors (LDL-R), increased uptake of LDL-C, and lower LDL-C plasmatic levels. Statins, ezetimibe, and PCSK9 inhibitors have been shown to be safe and effective in the post-ACS setting, providing a consistent decrease in ischemic event recurrence. However, these drugs remain largely underprescribed, and the consistent discrepancy between real-world data and guideline recommendations in terms of achieved LDL-C levels represents a leading issue in secondary prevention. Although the cost-effectiveness of these new therapeutic advancements has been clearly demonstrated, many concerns about the cost of some newer agents continue to limit their use, affecting the outcome of patients who experienced ACS. In spite of the fact that according to the current recommendations, a stepwise lipid-lowering approach should be adopted, several more recent data suggest a "strike early and strike strong" strategy, based on the immediate use of statins and, eventually, a dual lipid-lowering therapy, reducing as much as possible the changes in lipid-lowering drugs after ACS. This review aims to discuss the possible lipid-lowering strategies in post-ACS and to identify those patients who might benefit most from more powerful treatments and up-to-date management.

Identification of pathogenic GCK variants in patients with common type 2 diabetes can lead to discontinuation of pharmacological treatment

Background

Functionally disruptive variants in the glucokinase gene (GCK) cause a form of mild non-progressive hyperglycemia, which does not require pharmacological treatment. A substantial proportion of patients with type 2 diabetes (T2D) carry GCK variants. We aimed to investigate whether carriers of rare GCK variants diagnosed with T2D have a glycemic phenotype and treatment response consistent with GCK-diabetes.

Methods

Eight patients diagnosed with T2D from the Danish DD2 cohort who had previously undergone sequencing of GCK participated. Clinical examinations at baseline included an oral glucose tolerance test and continuous glucose monitoring. Carriers with a glycemic phenotype consistent with GCK-diabetes took part in a three-month treatment withdrawal.

Results

Carriers of pathogenic and likely pathogenic variants had lower median fasting glucose and C-peptide levels compared to carriers of variants of uncertain significance and benign variants (median fasting glucose: 7.3 (interquartile range: 0.4) mmol/l vs. 9.5 (1.6) mmol/l, p = 0.04; median fasting C-peptide 902 (85) pmol/l vs. 1535 (295) pmol/l, p = 0.03). Four participants who discontinued metformin treatment and one diet-treated participant were reevaluated after three months. There was no deterioration of HbA1c or fasting glucose (median baseline HbA1c: 49 (3) vs. 51 (6) mmol/mol after three months, p = 0.4; median baseline fasting glucose: 7.3 (0.4) mmol/l vs. 7.0 (0.6) mmol/l after three months, p = 0.5). Participants did not consistently fulfill best practice guidelines for GCK screening nor clinical criteria for monogenic diabetes.

Discussion

Carriers of pathogenic or likely pathogenic GCK variants identified by unselected screening in T2D should be reported, as they have a glycemic phenotype and treatment response consistent with GCK-diabetes. Variants of uncertain significance should be interpreted with care. Systematic genetic screening of patients with common T2D receiving routine care can lead to the identification and precise care of patients with misclassified GCK-diabetes who are not identifiable through common genetic screening criteria.

Type 1 diabetes, periodontal health, and a familial history of hyperlipidaemia is associated with oral microbiota in children: a cross-sectional study

BACKGROUND

Hyperlipidaemia may play a significant role in the interrelationship between type 1 diabetes (T1D) and periodontal disease. A potential mechanism that links these three aspects together is the oral microbiota. We wanted to determine if there is an association between hyperlipidaemia, periodontal disease, and the oral microbiota of children with T1D, as this has not yet been explored.

METHODS

In a post-hoc, cross-sectional study using 16S rRNA gene sequencing, we explored links between oral bacterial diversity and composition of gingival swab samples from 72 children with T1D to periodontal risk factors and hyperlipidaemia status of first-degree relatives. While multiple periodontal risk factors were assessed, we used periodontal pocket depth of 3 mm to characterise periodontal risk. As periodontal pocket depth confounded the analysis of familial history of hyperlipidaemia, a multivariate analyses were performed (i.e., no periodontal risk markers in children with or without a family history of hyperlipidaemia were compared to counterparts who did not have periodontal risk markers) to examine linkages between these factors and diversity and composition of the microbiome.

RESULTS

In participants with no periodontitis risk, children with a family history of dyslipidemia had different bacterial diversity and composition compared to those without a familar hisitory. In contrast, such differences did not exist in the children with periodontal risk, whether or not they had a family history of hyperlipidaemia. Co-occurrence networks showed that these differences in children with no periodontists risk were linked to the presence of fewer oral microbial networks, but more microbes linked to mature plaque structures. In contrast, children with periodontal risk markers, regardless of family history of hyperlipidaemia, contained co-occurrence networks that were associated with microbes linked to periodontal disease.

CONCLUSIONS

In children diagnosed with T1D, our findings support an association between oral microbiota and two different exposure variables: familial history of hyperlipidaemia and periodontal risk factors.

Hypertriglyceridemia in young adults with a 22q11.2 microdeletion

OBJECTIVE

Mild to moderate hypertriglyceridemia is a condition often associated with obesity and diabetes, with as yet incomplete knowledge of underlying genetic architecture. The 22q11.2 microdeletion is associated with multimorbidity, including increased risk of obesity and diabetes. In this study, we sought to investigate whether the 22q11.2 microdeletion was associated with mild to moderate hypertriglyceridemia (1.7-10 mmol/L).

DESIGN

This was a cohort study comparing 6793 population-based adults and 267 with a 22q11.2 microdeletion aged 17-69 years, excluding those with diabetes or on statins.

METHODS

We used binomial logistic regression modeling to identify predictors of hypertriglyceridemia, accounting for the 22q11.2 microdeletion, male sex, BMI, ethnicity, age, and antipsychotic medications.

RESULTS

The 22q11.2 microdeletion was a significant independent predictor of mild to moderate hypertriglyceridemia (odds ratio (OR): 2.35, 95% CI: 1.70-3.26). All other factors examined were also significant predictors (OR: 1.23-2.10), except for antipsychotic medication use. Within the 22q11.2 microdeletion subgroup, only male sex (OR: 3.10, 95% CI: 1.77-5.44) and BMI (OR: 1.63, 95% CI: 1.14-1.98) were significant predictors of hypertriglyceridemia, evident at mean age 31.2 years.

CONCLUSIONS

The 22q11.2 microdeletion is associated with hypertriglyceridemia even when accounting for other known risk factors for elevated triglycerides. This effect is seen in young adulthood (76.6% were <40 years), in the absence of diabetes, and irrespective of antipsychotics, suggesting that the 22q11.2 microdeletion may represent an unrecognized genetic risk factor for hypertriglyceridemia, providing novel opportunities for animal and cellular models. Early dyslipidemia screening and management strategies would appear prudent for individuals with 22q11.2 microdeletions.

Association between Health-Related Physical Fitness and Risk of Dyslipidemia in University Staff: A Cross-Sectional Study and a ROC Curve Analysis

Background: This study aimed to assess the relationship between dyslipidemia (DL) risk and health-related physical fitness (HPF) and evaluated the prognostic value of HPF for risk of DL. Methods: A total of 776 university staff members were recruited, of which 407 were females, and 369 males. Blood samples and HPF tests were collected from all participants after 12 h fasting. Results: The prevalence of DL was 41.77% and 51.49% in female and male university staff members, respectively, and there was no significant difference between genders (χ2 = 2.687, p = 0.101). According to the logistic regression analysis, age, male sex, GLU, hypertension, BMI, BF, WHtR, and LAP were significant risk factors for DL (p < 0.05), VCI and, SAR were significant protective factors for DL (p < 0.05), and SMI, GS, and VG were not significantly associated with the risk of DL. The area under the receiver-operating characteristic (ROC) curve (AUC) analysis indicated that, LAP (AUC: 0.730, 95CI%: 0.697–0.762), WHtR (AUC: 0.626, 95CI%: 0.590–0.660), and BMI (AUC: 0.599, 95CI%: 0.563–0.634) are valid predictors of DL, and LAP and WHtR perform better than BMI (Z = 8.074, p < 0.001) in predicting DL in male and female university staff members. Conclusion: The risk of DL is significantly related to body composition, cardiorespiratory fitness, and flexibility. LAP and WHtR perform better than BMI in predicting risk of DL in male and female university staff members.

Serum albumin mediates the effect of multiple per- and polyfluoroalkyl substances on serum lipid levels

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are synthetically manufactured chemicals recognized to be toxic, bioaccumulative, and persistent. Previous studies on PFAS exposure and serum lipid levels have mainly focused on individual PFASs; however, the influence of multiple-PFAS exposure on the serum lipid profile remains unclear. This study was performed to evaluate the combined effects of multiple PFASs on serum lipid levels. Based on the National Health and Nutrition Examination Survey (NHANES) data (2011-2014), we first established a linear regression model to estimate the association between single-PFAS exposure and the serum lipid profile. Then, a weighted quantile sum (WQS) regression model and a Bayesian kernel machine regression (BKMR) model were used to evaluate the effects of multiple-PFAS exposure on the serum lipid profile. A mediating effect model was used to assess how albumin mediates these effects. We found that PFASs were significantly associated with the levels of serum lipids, including high-density lipoprotein (HDL), low-density lipoprotein (LDL) and total cholesterol (TC). The WQS index was significantly correlated with the levels of HDL (β: 2.03, 95% CI: 0.74-3.32, P-value = 0.002), LDL (β: 4.16, 95% CI: 1.07-7.24, P-value = 0.008) and TC (β: 6.54, 95% CI: 3.00-10.1, P-value < 0.001). In the BKMR analysis, our results demonstrated that the effect of PFASs on serum lipids increased significantly when the concentrations of the PFASs were at their 60th percentiles or above compared to those at their 50th percentile. Mediation analysis showed that albumin mediated the effects of selected PFASs on the levels of serum lipids except for triglycerides (TG). PFAS exposure was correlated with the levels of serum lipids, and this correlation was mediated by albumin. Our results suggest that a comprehensive evaluation of multi-PFAS exposure could better characterize real-life exposure compared with single-PFAS exposure.

Interaction of polymorphisms in APOA4-APOA5-ZPR1-BUD13 gene cluster and sleep duration on 5-year lipid changes in middle aged and older Chinese

STUDY OBJECTIVES

Lipid profiles are influenced by both genetic and environmental factors. Genetic variants in the APOA4-APOA5-ZPR1-BUD13 gene cluster and aberrant sleep duration were independently identified to be associated with lipids in previous studies. We aimed to investigate whether sleep duration modified the genetic associations with longitudinal lipids changes.

METHODS

Four single nucleotide polymorphisms (SNPs), rs17119975, rs651821, rs7396835, and rs964184 in the APOA4-APOA5-ZPR1-BUD13 gene cluster were genotyped among 8648 apparently healthy subjects from the Dongfeng-Tongji (DFTJ) cohort. Information on sleep duration was obtained by questionnaires. Changes in total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), were evaluated from baseline to 5-year follow-up.

RESULTS

After multivariate adjustments, we found that rs651821 and weighted genetic risk score (GRS) were significantly associated with increased triglyceride, and the genetic association with triglyceride change consistently strengthened across sleep duration categories. The differences in triglyceride changes per increment of risk allele for rs651821 were 0.028 (SE = 0.017, p = 0.112), 0.051 (SE = 0.009, p < 0.001), and 0.064 (SE = 0.016, p < 0.001) in individuals with sleep duration ≤7, >7-<9, and ≥9 h, respectively (p interaction = 0.031). The GRS also showed a significant interaction with sleep duration categories for triglyceride change (p interaction = 0.010). In addition, all of the four SNPs and GRS were inversely related to HDL-c changes.

CONCLUSIONS

Longer sleep duration might exacerbate the adverse effects of SNPs in APOA4-APOA5-ZPR1-BUD13 gene cluster on 5-year triglyceride changes.

Associations between age and dyslipidemia are differed by education level: The Cardiovascular and Metabolic Diseases Etiology Research Center (CMERC) cohort

Background

Dyslipidemia is a multifactorial disorder, which arises from complex interactions among genetic and environmental risk factors. Previous studies have established the deteriorating effect of aging on lipid profiles. However, little is known about the role of education level, a stable marker of socioeconomic status, which reflect modifiability of lifestyle risk factors. Therefore, we examined the association between age and individual dyslipidemia parameter across education level among healthy, middle-aged Korean women.

Methods

From 2049 middle-aged women, education attainment was classified into completion of elementary school or below, middle school, high school, college or above. Dyslipidemia was assessed in adherence to the 2018 Korean Dyslipidemia Treatment Guideline. Multivariable logistic regression and generalized linear model tested for associations between age and dyslipidemia parameter across education level and other known risk factors, including menopause, obesity, and current drinking and smoking.

Results

In this cross-sectional analysis, the prevalence of each dyslipidemia parameter was significantly different by age and education level. The odds ratio (OR) for dyslipidemia was higher among participants who were older and had received higher education (OR = 2.31, p for interaction = 0.008) than younger and low education counterpart. The interaction between age and education level remained significant for hypercholesterolemia (p for interaction = 0.003) and hyper-LDL-cholesterolemia (p for interaction = 0.002).

Conclusions

Separate examination of individual dyslipidemia parameter indicated varying degree of interaction with age and education level. Such results imply that each type of lipid abnormality may arise from and be exacerbated by heterogeneous composition of biological and lifestyle risk factors, which may be reflected by education level.

Lipid and Creatinine Adjustment to Evaluate Health Effects of Environmental Exposures

PURPOSE OF REVIEW

Urine- and serum-based biomarkers are useful for assessing individuals' exposure to environmental factors. However, variations in urinary creatinine (a measure of dilution) or serum lipid levels, if not adequately corrected for, can directly impact biomarker concentrations and bias exposure-disease association measures.

RECENT FINDINGS

Recent methodological literature has considered the complex relationships between creatinine or serum lipid levels, exposure biomarkers, outcomes, and other potentially relevant factors using directed acyclic graphs and simulation studies. The optimal measures of urinary dilution and serum lipids have also been investigated. Existing evidence supports the use of covariate-adjusted standardization plus creatinine adjustment for urinary biomarkers and standardization plus serum lipid adjustment for lipophilic, serum-based biomarkers. It is unclear which urinary dilution measure is best, but all serum lipid measures performed similarly. Future research should assess methods for pooled biomarkers and for studying diseases and exposures that affect creatinine or serum lipids directly.

Environmental Chemicals in Urine and Blood: Improving Methods for Creatinine and Lipid Adjustment

BACKGROUND

Investigators measuring exposure biomarkers in urine typically adjust for creatinine to account for dilution-dependent sample variation in urine concentrations. Similarly, it is standard to adjust for serum lipids when measuring lipophilic chemicals in serum. However, there is controversy regarding the best approach, and existing methods may not effectively correct for measurement error.

OBJECTIVES

We compared adjustment methods, including novel approaches, using simulated case-control data.

METHODS

Using a directed acyclic graph framework, we defined six causal scenarios for epidemiologic studies of environmental chemicals measured in urine or serum. The scenarios include variables known to influence creatinine (e.g., age and hydration) or serum lipid levels (e.g., body mass index and recent fat intake). Over a range of true effect sizes, we analyzed each scenario using seven adjustment approaches and estimated the corresponding bias and confidence interval coverage across 1,000 simulated studies.

RESULTS

For urinary biomarker measurements, our novel method, which incorporates both covariate-adjusted standardization and the inclusion of creatinine as a covariate in the regression model, had low bias and possessed 95% confidence interval coverage of nearly 95% for most simulated scenarios. For serum biomarker measurements, a similar approach involving standardization plus serum lipid level adjustment generally performed well.

CONCLUSIONS

To control measurement error bias caused by variations in serum lipids or by urinary diluteness, we recommend improved methods for standardizing exposure concentrations across individuals.

CETP genotype and changes in lipid levels in response to weight-loss diet intervention in the POUNDS LOST and DIRECT randomized trials

Little is known about whether cholesteryl ester transfer protein (CETP) genetic variation may modify the effect of weight-loss diets varying in fat content on changes in lipid levels. We analyzed the interaction between the CETP variant rs3764261 and dietary interventions on changes in lipid levels among 732 overweight/obese adults from a 2 year randomized weight-loss trial [Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST)], and replicated the findings in 171 overweight/obese adults from an independent 2 year weight-loss trial [Dietary Intervention Randomized Controlled Trial (DIRECT)]. In the POUNDS LOST, participants with the CETP rs3764261 CC genotype on the high-fat diet had larger increases in HDL cholesterol (P = 0.001) and decreases in triglycerides (P = 0.007) than those on the low-fat diet at 6 months, while no significant difference between these two diets was observed among participants carrying other genotypes. The gene-diet interactions on changes in HDL-cholesterol and tri-glyc-erides were replicated in the DIRECT (pooled P for interaction ≤ 0.01). Similar results on trajectory of changes in HDL cholesterol and triglycerides over the 2 year intervention were observed in both trials. Our study provides replicable evidence that individuals with the CETP rs3764261 CC genotype might derive greater effects on raising HDL cholesterol and lowering triglycerides by choosing a low-carbohydrate/high-fat weight-loss diet instead of a low-fat diet.

Nutritional status, genetic susceptibility, and insulin resistance--important precedents to atherosclerosis

Atherosclerosis is a progressive disease that starts early in life and is manifested clinically as coronary artery disease (CAD), cerebrovascular disease, or peripheral artery disease. CAD remains the leading cause of morbidity and mortality in Western society despite the great advances made in understanding its underlying pathophysiology. The key risk factors associated with CAD include hypercholesterolemia, hypertension, poor diet, obesity, age, male gender, smoking, and physical inactivity. Genetics also play an important role that may interact with environmental factors, including diet, nutritional status, and physiological parameters. Furthermore, certain chronic inflammatory conditions also predispose to the development of CAD. The spiraling increase in obesity rates worldwide has made it more pertinent than ever before to understand the metabolic perturbations that link over nutrition to enhanced cardiovascular risk. Great breakthroughs have been made at the pharmacological level to manage CAD; statins and aspirin have revolutionized treatment of CAD and prolonged lifespan. Nonetheless, lifestyle intervention prior to clinical presentation of CAD symptoms would negate/delay the need for chronic pharmacotherapy in at-risk individuals which in turn would relieve healthcare systems of a costly burden. Throughout this review, we debate the relative impact of nutrition versus genetics in driving CAD. We will investigate how overnutrition affects adipose tissue biology and drives IR and will discuss the subsequent implications for the cardiovascular system. Furthermore, we will discuss how lifestyle interventions including diet modification and weight loss can improve both IR and metabolic dyslipidemia that is associated with obesity. We will conclude by delving into the concept that nutritional status interacts with genetic susceptibility, such that perhaps a more personalized nutrition approach may be more effective in determining diet-related risk as well as response to nutritional interventions.

Systematic evaluation of environmental factors: persistent pollutants and nutrients correlated with serum lipid levels

Background Both genetic and environmental factors contribute to triglyceride, low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) levels. Although genome-wide association studies are currently testing the genetic factors systematically, testing and reporting one or a few factors at a time can lead to fragmented literature for environmental chemical factors. We screened for correlation between environmental factors and lipid levels, utilizing four independent surveys with information on 188 environmental factors from the Centers of Disease Control, National Health and Nutrition Examination Survey, collected between 1999 and 2006.

Methods We used linear regression to correlate each environmental chemical factor to triglycerides, LDL-C and HDL-C adjusting for age, age², sex, ethnicity, socio-economic status and body mass index. Final estimates were adjusted for waist circumference, diabetes status, blood pressure and survey. Multiple comparisons were controlled for by estimating the false discovery rate and significant findings were tentatively validated in an independent survey.

Results We identified and validated 29, 9 and 17 environmental factors correlated with triglycerides, LDL-C and HDL-C levels, respectively. Findings include hydrocarbons and nicotine associated with lower HDL-C and vitamin E (γ-tocopherol) associated with unfavourable lipid levels. Higher triglycerides and lower HDL-C were correlated with higher levels of fat-soluble contaminants (e.g. polychlorinated biphenyls and dibenzofurans). Nutrients and vitamin markers (e.g. vitamins B, D and carotenes), were associated with favourable triglyceride and HDL-C levels.

Conclusions Our systematic association study has enabled us to postulate about broad environmental correlation to lipid levels. Although subject to confounding and reverse causality bias, these findings merit evaluation in additional cohorts.

Consistency between cross-sectional and longitudinal SNP: blood lipid associations

Various studies have linked different genetic single nucleotide polymorphisms (SNPs) to different blood lipids (BL), but whether these "connections" were identified using cross-sectional or longitudinal (i.e., changes over time) designs has received little attention. Cross-sectional and longitudinal assessments of BL [total, high-, low-density lipoprotein cholesterol (TC, HDL, LDL), triglycerides (TG)] and non-genetic factors (body mass index, smoking, alcohol intake) were measured for 2,002 Geneva, Switzerland, adults during 1999-2008 (two measurements, median 6 years apart), and 20 SNPs in 13 BL metabolism-related genes. Fixed and mixed effects repeated measures linear regression models, respectively, were employed to identify cross-sectional and longitudinal SNP:BL associations among the 1,516 (76%) study participants who reported not being treated for hypercholesterolemia at either measurement time. One-third more (12 vs. 9) longitudinal than cross-sectional associations were found [Bonferroni-adjusted two-tailed p < 0.00125 (=0.05/2)/20) for each of the four ensembles of 20 SNP:individual BL associations tested under the two study designs]. There was moderate consistency between the cross-sectional and longitudinal findings, with eight SNP:BL associations consistently identified across both study designs: [APOE.2 and APOE.4 (rs7412 and rs429358)]:TC; HL/LIPC (rs2070895):HDL; [APOB (rs1367117), APOE.2 and APOE.4 (rs7412 and rs429358)]:LDL; [APOA5 (rs2072560) and APOC III (rs5128)]:TG. The results suggest that cross-sectional studies, which include most genome-wide association studies (GWAS), can assess the large majority of SNP:BL associations. In the present analysis, which was much less powered than a GWAS, the cross-sectional study was around 2/3 (67%) as efficient as the longitudinal study.

The effect of alcohol and tobacco consumption, and apolipoprotein E genotype, on the age of onset in Alzheimer's disease

OBJECTIVE

This study examined the association between a history of heavy alcohol use and smoking, presence of the apolipoprotein-E epsilon 4 allele (APOE epsilon4), and age of disease onset in a community dwelling sample of 685 Alzheimer's disease (AD) patients spanning three ethnic groups.

DESIGN

Cross-sectional study of AD patients evaluated at a University-affiliated outpatient memory disorders clinic.

SUBJECTS

A clinic-based cohort of white non-Hispanic (WNH; n = 397), white Hispanic (WH; n = 264), and African-American (AA; n = 24) patients diagnosed with possible or probable AD according to NINCDS-ADRDA diagnostic criteria.

MEASUREMENTS

The age of onset of AD was obtained from a knowledgeable family member. All patients were assessed for APOE genotype. History of alcohol and tobacco consumption prior to the onset of dementia was obtained via an interview with the patient and the primary caregiver. A history of heavy drinking was defined as >2 drinks per day and a history of heavy smoking was defined as > or =1 pack per day.

RESULTS

Presence of an APOE epsilon4 allele, a history of heavy drinking, or a history of heavy smoking were each associated with an earlier onset of AD by 2-3 years. Patients with all three risk factors were likely to be diagnosed with AD nearly 10 years earlier than those with none of the risk factors.

CONCLUSION

The results suggest that APOE epsilon4 and heavy drinking and heavy smoking lower the age of onset for AD in an additive fashion.

Impact of early parental child-rearing behavior on young adults' cardiometabolic risk profile: a prospective study

OBJECTIVE

To examine prospectively whether early parental child-rearing behavior is a predictor of cardiometabolic outcome in young adulthood when other potential risk factors are controlled. Metabolic factors associated with increased risk for cardiovascular disease have been found to vary, depending on lifestyle as well as genetic predisposition. Moreover, there is evidence suggesting that environmental conditions, such as stress in pre- and postnatal life, may have a sustained impact on an individual's metabolic risk profile.

METHODS

Participants were drawn from a prospective, epidemiological, cohort study followed up from birth into young adulthood. Parent interviews and behavioral observations at the age of 3 months were conducted to assess child-rearing practices and mother-infant interaction in the home setting and in the laboratory. In 279 participants, anthropometric characteristics, low-density lipoprotein and high-density lipoprotein cholesterol, apolipoproteins, and triglycerides were recorded at age 19 years. In addition, structured interviews were administered to the young adults to assess indicators of current lifestyle and education.

RESULTS

Adverse early-life interaction experiences were significantly associated with lower levels of high-density lipoprotein cholesterol and apolipoprotein A1 in young adulthood. Current lifestyle variables and level of education did not account for this effect, although habitual smoking and alcohol consumption also contributed significantly to cardiometabolic outcomes.

CONCLUSIONS

These findings suggest that early parental child-rearing behavior may predict health outcome in later life through its impact on metabolic parameters in adulthood.

Genetic-epidemiological evidence on genes associated with HDL cholesterol levels: a systematic in-depth review

High-density lipoprotein (HDL) particles exhibit multiple antiatherogenic effects. They are key players in the reverse cholesterol transport which shuttles cholesterol from peripheral cells (e.g. macrophages) to the liver or other tissues. This complex process is thought to represent the basis for the antiatherogenic properties of HDL particles. The amount of cholesterol transported in HDL particles is measured as HDL cholesterol (HDLC) and is inversely correlated with the risk for coronary artery disease: an increase of 1mg/dL of HDLC levels is associated with a 2% and 3% decrease of the risk for coronary artery disease in men and women, respectively. Genetically determined conditions with high HDLC levels (e.g. familial hyperalphalipoproteinemia) often coexist with longevity, and higher HDLC levels were found among healthy elderly individuals. HDLC levels are under considerable genetic control with heritability estimates of up to 80%. The identification and characterization of genetic variants associated with HDLC concentrations can provide new insights into the background of longevity. This review provides an extended overview on the current genetic-epidemiological evidence from association studies on genes involved in HDLC metabolism. It provides a path through the jungle of association studies which are sometimes confusing due to the varying and sometimes erroneous names of genetic variants, positions and directions of associations. Furthermore, it reviews the recent findings from genome-wide association studies which have identified new genes influencing HDLC levels. The yet identified genes together explain only a small amount of less than 10% of the HDLC variance, which leaves an enormous room for further yet to be identified genetic variants. This might be accomplished by large population-based genome-wide meta-analyses and by deep-sequencing approaches on the identified genes. The resulting findings will probably result in a re-drawing and extension of the involved metabolic pathways of HDLC metabolism.

Gender-specific differences in the kinetics of nonfasting TRL, IDL, and LDL apolipoprotein B-100 in men and premenopausal women

OBJECTIVE

To investigate mechanisms underlying gender differences in serum lipoprotein concentrations, the kinetic behavior of apoB-100 was assessed.

METHODS AND RESULTS

Twenty subjects (<50 years; 12 men and 8 premenopausal women) were provided a Western diet for 4 to 6 weeks, after which the kinetics of apoB-100 in triglyceride-rich, intermediate-density, and low-density lipoprotein (TRL, IDL, and LDL) were determined in the fed state. Nonfasting plasma TC, LDL-C, and triglyceride concentrations were 23%, 34%, and 57% lower, respectively, in the women compared with men. Plasma TRL and LDL apoB 100 pool sizes were lower by 40% and 30%, respectively. These differences were accounted for by higher TRL and LDL apoB 100 fractional catabolic rates (FCR), rather than differences in production rates (PR). Plasma TRL-C and LDL-C were positively correlated with TRL and LDL apoB 100 concentrations and pool size, and negatively correlated with TRL and LDL apoB 100 FCR (women: r=-0.59, P<0.01 and r=-0.54, P<0.04, and men: r=-0.43, P<0.05 and r=-0.44, P<0.05). No significant associations were observed between plasma TRL-C and LDL-C and PR.

CONCLUSIONS

These data suggest the mechanism for lower TRL-C and LDL-C concentrations in women was determined predominantly by higher TRL and LDL FCR rather than lower PR. This could explain, in part, the lower CVD risk in premenopausal women relative to men.

Lifelong reduction of LDL-cholesterol related to a common variant in the LDL-receptor gene decreases the risk of coronary artery disease--a Mendelian Randomisation study

BACKGROUND

Rare mutations of the low-density lipoprotein receptor gene (LDLR) cause familial hypercholesterolemia, which increases the risk for coronary artery disease (CAD). Less is known about the implications of common genetic variation in the LDLR gene regarding the variability of cholesterol levels and risk of CAD.

METHODS

Imputed genotype data at the LDLR locus on 1 644 individuals of a population-based sample were explored for association with LDL-C level. Replication of association with LDL-C level was sought for the most significant single nucleotide polymorphism (SNP) within the LDLR gene in three European samples comprising 6 642 adults and 533 children. Association of this SNP with CAD was examined in six case-control studies involving more than 15 000 individuals.

FINDINGS

Each copy of the minor T allele of SNP rs2228671 within LDLR (frequency 11%) was related to a decrease of LDL-C levels by 0.19 mmol/L (95% confidence interval (CI) [0.13-0.24] mmol/L, p = 1.5x10(-10)). This association with LDL-C was uniformly found in children, men, and women of all samples studied. In parallel, the T allele of rs2228671 was associated with a significantly lower risk of CAD (Odds Ratio per copy of the T allele: 0.82, 95% CI [0.76-0.89], p = 2.1x10(-7)). Adjustment for LDL-C levels by logistic regression or Mendelian Randomisation models abolished the significant association between rs2228671 with CAD completely, indicating a functional link between the genetic variant at the LDLR gene locus, change in LDL-C and risk of CAD.

CONCLUSION

A common variant at the LDLR gene locus affects LDL-C levels and, thereby, the risk for CAD.

Lipoprotein lipase HindIII polymorphism influences HDL-cholesterol levels in statin-treated patients with coronary artery disease

BACKGROUND

HDL-cholesterol (HDL-C) is a recognized athero-protective factor and low levels of HDL-C occur frequently in patients with coronary artery disease. Regulation of HDL-C level most probably results from the interaction of genes involved in lipoprotein metabolism and also from non-genetic factors. We studied associations and interactions among HindIII polymorphisms of the lipoprotein lipase gene LPL and selected non-genetic factors with respect to HDL-C levels in patients with coronary artery disease.

PATIENTS AND METHODS

288 Slovak patients (35% women) with documented coronary artery disease, age (mean +/- SEM) 60 +/- 1 years and BMI 29 +/- 0.3 kg/m(2), were examined and genotyped for LPL HindIII (rs320) using a PCR/RFLP method. HDL-C levels were determined in a direct enzymatic assay.

RESULTS

In the sample overall there were no significant differences across the LPL genotypes in adjusted HDL-C levels or in other lipids, although a trend toward higher HDL-C and lower triglycerides in H-H- homozygotes was observed. Multiple linear regression identified a significant interaction between LPL HindIII and statin treatment, which together with sex and diabetes explained 12.1% of HDL-C variance. Accordingly, in statin-treated patients we observed significant stepwise increments of the HDL-C level related to the increasing number of H- alleles (P = 0.04 for linear trend), whereas no such association was observed in patients without hypolipidemic treatment. H-H- homozygotes had a 16% (0.19 mmol/l) higher level of HDL-C than the H+H+ homozygotes (P = 0.06).

CONCLUSION

HDL-C may be influenced by an interaction between statin treatment and LPL HindIII genotype. However, the effect of this interaction appears to be small when compared with the effect of non-genetic factors. This finding requires replication in a pharmacogenetic study.

Differential diagnosis of familial high density lipoprotein deficiency syndromes

Monogenic high density lipoprotein (HDL) deficiency, because of defects in the genes of apolipoprotein A-I (apoA-I), adenosine triphosphate binding cassette transporter A1 (ABCA1) or lecithin:cholesterol acyltransferase (LCAT), can be assumed in patients with HDL cholesterol levels below the fifth percentile within a given population. As in a first step underlying diseases should be excluded. Patients with a virtual absence of HDL must undergo careful physical examination to unravel the clinical hallmarks of certain HDL deficiency syndromes. In addition, family studies should be initiated, to demonstrate the vertical transmission of the low HDL cholesterol phenotype. Definitive diagnosis requires specialized biochemical tests and the demonstration of a functionally-relevant mutation in one of the three discussed candidate genes. As yet no routinely used drug is able to increase HDL cholesterol levels in patients with familial low HDL cholesterol so that prevention of cardiovascular disease in these patients must be focused on the avoidance and treatment of additional risk factors.