The lipoprotein lipase gene serine 447 stop variant influences hypertension-induced left ventricular hypertrophy and risk of coronary heart disease

Association of the lipoprotein lipase gene Ser447Ter polymorphism with hypertension and blood pressure variation: evidence from an updated meta-analysis

The polymorphism of lipoprotein lipase (LPL) gene Ser447Ter (S447X) has long been linked to hypertension and blood pressure variation, but the established data remained controversial. To better elucidate this inconsistency, a meta-analysis was conducted. We comprehensively searched electronic databases, including Pubmed, EMBASE, China National Knowledge Infrastructure (CNKI), Web of Science, for all literatures with the last update on February 2016. The strength of association was calculated by using odds ratios (ORs) and weighted mean differences (WMDs) with corresponding 95% confidence intervals (CIs). Further stratified analyses, cumulative meta-analysis analysis, and sensitivity analyses were performed. A total of 14 studies (3592 cases and 4643 controls) for hypertension and 14 studies (n = 9254) for blood pressure were included. Overall, significant associations were revealed between S447X polymorphism and hypertension risk using allelic comparison (OR = 0.86, 95%CI 0.77 to 0.96), heterozygote comparison (OR = 0.85, 95%CI 0.75 to 0.96), and the dominant model (OR = 0.85, 95%CI 0.75 to 0.96), especially in Asians. Furthermore, in subgroup analyses restricted to the population-based controls studies, the high-quality studies, and the large sample size studies, these significant associations were still observed. As for blood pressure association, significant reductions of systolic blood pressure (WMD = -1.25 mmHg, 95%CI -2.25 to -0.25 mmHg) and diastolic blood pressure (WMD = -1.91 mmHg, 95%CI -3.25 to -0.56 mmHg) levels were found using dominant model. No publication bias was observed in any comparison model. Therefore, current meta-analysis suggested that the LPL S447X polymorphism is likely to be a protective factor in the development of hypertension.

Impact of Lipoprotein Lipase Gene Polymorphism, S447X, on Postprandial Triacylglycerol and Glucose Response to Sequential Meal Ingestion

Lipoprotein lipase (LPL) is a key rate-limiting enzyme for the hydrolysis of triacylglycerol (TAG) in chylomicrons and very low-density lipoprotein. Given that postprandial assessment of lipoprotein metabolism may provide a more physiological perspective of disturbances in lipoprotein homeostasis compared to assessment in the fasting state, we have investigated the influence of two commonly studied LPL polymorphisms (rs320, HindIII; rs328, S447X) on postprandial lipaemia, in 261 participants using a standard sequential meal challenge. S447 homozygotes had lower fasting HDL-C (p = 0.015) and a trend for higher fasting TAG (p = 0.057) concentrations relative to the 447X allele carriers. In the postprandial state, there was an association of the S447X polymorphism with postprandial TAG and glucose, where S447 homozygotes had 12% higher TAG area under the curve (AUC) (p = 0.037), 8.4% higher glucose-AUC (p = 0.006) and 22% higher glucose-incremental area under the curve (IAUC) (p = 0.042). A significant gene–gender interaction was observed for fasting TAG (p = 0.004), TAG-AUC (P_interaction = 0.004) and TAG-IAUC (P_interaction = 0.016), where associations were only evident in men. In conclusion, our study provides novel findings of an effect of LPL S447X polymorphism on the postprandial glucose and gender-specific impact of the polymorphism on fasting and postprandial TAG concentrations in response to sequential meal challenge in healthy participants.

The lipoprotein lipase (LPL) S447X gain of function variant involves increased mRNA translation

OBJECTIVE

A common gain-of-function LPL variant, LPLS447X, has favorable clinical features and involves a C→G base change at nucleotide 1595 of the LPL cDNA, along with a haplotype, which includes other non-coding SNPs. The mechanism for the LPL gain-in-function is not clear. LPL translation is regulated by epinephrine by an RNA-protein complex, consisting of PKA subunits and an A kinase anchoring protein (AKAP), which targets the 3'UTR.

METHODS

To examine LPL translation of the LPLS447X variant, in vitro translation of LPL mRNA constructs was studied in the presence of cytoplasmic extracts from 3T3-F442A adipocytes treated with/without epinephrine.

RESULTS

When the C→G base change at nucleotide 1595 was introduced, LPL mRNA was less susceptible to inhibition by the adipocyte extract. Similarly, a lessened susceptibility to translation inhibition occurred when the complete haplotype was constructed in the full-length 3.6 kb LPL mRNA, when an irrelevant coding sequence was introduced into the LPL mRNA construct, and in response to the use of components of the RNA binding complex (PKA C and R subunits, and KH region of AKAP149).

CONCLUSION

These studies suggest that the LPLS447X gain of function may be due to the base change in the LPL mRNA resulting in a decreased susceptibility to translational inhibition.

Meta-based association of the lipoprotein lipase gene S447X variant with hypertension and blood pressure variation

Association of the lipoprotein lipase (LPL) gene S447X variant with hypertension has been investigated extensively, whereas the results are often irreproducible. We therefore conducted a meta-analysis to examine whether S447X variant was associated with hypertension and blood pressure variation. Case-control reports published in English language and humans were identified from MEDLINE, EMBASE and Web of Science search engines as of 10 December 2009. Fixed-effects model was applied to pool data in the absence of between-studies heterogeneity, and random-effects model otherwise. A total of five studies (960 cases and 1145 controls) for hypertension and four studies (n=2777) for blood pressure were included. Compared with 447SS homogeneous carriers, those with 447X variant had a lower risk of hypertension (odds ratio (OR)=0.78; 95% confidence interval (CI): 0.62-0.98; P=0.03), and this effect reached significance under the fixed-effects model (I(2)=30% and P=0.22). Similarly, compared with 447S allele carriers, those with 447X allele carriers also had a lower risk of hypertension (OR=0.79; 95% CI: 0.64-0.98; P=0.03). In case of pregnancy-induced hypertension, no significance was observed (P>0.05). As for blood pressure association, there was no significant difference between 447X variant and 447SS homogeneous carriers for both systolic and diastolic blood pressure in the whole population, even stratified by gender (P>0.05). The Egger test told no publication bias for all associations. This meta-analysis demonstrated that LPL gene S447X variant was significantly associated with hypertension and showed no obvious relation with pregnancy-induced hypertension and blood pressure variation.

The contribution of gene-environment interaction to psychopathology

The study of gene-environment interaction (G x E) constitutes an area of significant social and clinical significance. Different types of research study designs are being used to investigate the contribution of G x E to psychopathology, although the term G x E has also been used and interpreted in different ways. Despite mixed evidence that G x E contributes to psychopathology, some promising and consistent findings are emerging. Evidence is reviewed in relation to depression, antisocial behavior, schizophrenia, and attention-deficit/hyperactivity disorder. Although findings from various research designs have different meaning, interestingly much of the evidence with regard to the contribution of G x E that has arisen from twin and adoption studies has been for antisocial behavior and depression. It is for these same forms of psychopathology that molecular genetic evidence of G x E has also been most convincing. Finally, current and anticipated methodological challenges and implications for future research in this area are considered.

Angiotensin-Converting Enzyme Genotype Interacts With Systolic Blood Pressure to Determine Coronary Heart Disease Risk in Healthy Middle-Aged Men

The impact of the ACE I/D polymorphism on coronary heart disease (CHD) risk is modest at most, however it may act as a modifier gene. ACE genotype was determined in 2711 healthy middle-aged men (mean age 56 years) followed for 15 years. No genotype-CHD risk association was found, but when analyzed by quartiles of systolic blood pressure (SBP), compared with II homozygotes, carriage of each additional D allele was protective at lower SBP, but in the highest quartile (SBP >150 mm Hg) conferred almost 1.5 times the risk for CHD (genotype interaction P=0.003). When SBP was analyzed as a continuous variable, again a highly significant association was seen, with the hazard ratio ([95% CI]) for a 1 SD increase in SBP being 0.90 [0.70 to 1.15] for IIs and 1.40 [1.21 to 1.61] for ID/DD (genotype SBP interaction P=0.002). The D allele was protective against CHD at lower SBP but would overtake the II risk at higher SBP. In hypertension, the proinflammatory or prohypertrophic properties of angiotensin II may explain this association. The LPL S447X polymorphism also impacts on CHD risk through interaction with hypertension, and there was an additive action of these 2 polymorphisms and SBP on CHD risk (hazard ratio for 1 SD increase in SBP for combined genotypes 1.78 [1.30 to 2.45]). Thus in the presence of hypertension, common variation in "modifier" genes confers significant CHD risk.