Low serum PON1 activity: An independent risk factor for coronary artery disease in North–West Indian type 2 diabetics

The paraoxonase (PON1) gene polymorphisms are known to affect the PON1 activity and coronary artery disease (CAD) risk. Studies done so far have given conflicting results. In the present study, we determined the role of PON1 genetic variants and PON1 activity in the development of CAD in North–West Indian Punjabis, a distinct ethnic group, having high incidence of both CAD and type 2 diabetes. 300 angiographically proven CAD with type 2 diabetics and 250 type 2 diabetics with no clinically evident CAD were enrolled. Serum PON1 activity and genotyping of coding (Q192R, L55M) and promoter (− 909G/C, − 162A/G, − 108C/T) region polymorphisms were carried out and haplotypes were determined using PHASE software.     

Evidence for a role of CETP in HDL remodeling and cholesterol efflux: Role of cysteine 13 of CETP

Cholesteryl ester transfer protein (CETP), a key regulator of high-density lipoprotein (HDL) metabolism, induces HDL remodeling by transferring lipids between apolipoprotein B-containing lipoproteins and HDL, and/or by promoting lipid transfer between HDL subparticles. In this study, we investigated the mechanism as to how CETP induces the generation of lipid-poor particles (pre-β-HDL) from HDL, which increases ATP-binding cassette transporter 1-mediated cholesterol efflux. This CETP-dependent HDL remodeling is enhanced by the CETP modulator dalcetrapib both in plasma and isolated HDL. The interaction of dalcetrapib with cysteine 13 of CETP is required, since this effect was abolished when using mutant CETP in which cysteine 13 was substituted for a serine residue. Other thiol-containing compounds were identified as CETP modulators interacting with cysteine 13 of CETP. In order to mimic dalcetrapib-bound CETP, mutant CETP proteins were prepared by replacing cysteine 13 with the bulky amino acid tyrosine or tryptophan. The resultant mutants showed virtually no CETP-dependent lipid transfer activity but demonstrated preserved CETP-dependent pre-β-HDL generation. Overall, these data demonstrate that the two functions of CETP i.e., cholesteryl ester transfer and HDL remodeling can be uncoupled by interaction of thiol-containing compounds with cysteine 13 of CETP or by introducing large amino acid residues in place of cysteine 13.     

Apolipoprotein A5 T-1131C variant and risk for metabolic syndrome in obese adolescents

Background

Apolipoprotein A5 (APOA5) gene variants are associated with increased plasma triglycerides, a risk factor for metabolic syndrome (MS). The goal of the current study was the investigation of the distribution of T-1131C variant among obese adolescents with MS compared with healthy controls.

Subjects and methods

The study included 150 obese adolescents (75 males and 75 females) with MS and 204 age and sex matched normal healthy controls (100 males and 104 females). The mean age of the patients was 15.47 ± 2.54 years, ranged from 17 to 20 years. They were genotyped by polymerase chain reaction–restriction fragment length polymorphism for the mutation (T-1131C).

Results

The blood pressure, triglyceride and HOMA-R levels were significantly higher and HDL-C levels were significantly lower in carrier (TC + CC) compared to non-carrier (TT) MS patients. There was accumulation of − 1131C allele frequency in the MS group (31.33% vs. control group 11.76%), p < 0.001. The genotypes were in Hardy–Weinberg equilibrium both in the patients with metabolic syndrome and in the control subjects. Results of analysis of multiple regression models showed that the ApoA5 − 1131C carriers showed an increased incidence of MS (OR = 1.73, 95% CI: 1.41–2.11).

Conclusions

The present study suggests that the 1131T>C polymorphism is a risk factor for the development of metabolic syndrome in obese adolescents.     

AT2R − 1332 G:A polymorphism and its interaction with AT1R 1166 A:C,ACE I/D and MMP-9 − 1562 C:T polymorphisms: Risk factors for susceptibility to preeclampsia

The possible association of angiotensin type 2 receptor (AT2R) − 1332 G:A polymorphism with susceptibility to preeclampsia was studied in 252 women consisted of 155 women with preeclampsia and 97 healthy pregnant women. Also, the interaction of this polymorphism with angiotensin type 1 receptor (AT1R) 1166 A:C, angiotensin converting enzyme insertion/deletion (ACE I/D) and also with matrix metalloproteinase-9 (MMP-9) − 1562 C:T polymorphism was investigated. The AT2R − 1332 G:A polymorphism was detected using PCR–RFLP method. Significantly higher frequencies of GG+GA genotype and G allele of AT2R were observed in mild (80.2%, p = 0.003 and 47.5%, p = 0.012, respectively) and severe (77.8%, p = 0.034 and 48.1%, p = 0.026, respectively) preeclampsia compared to controls (60.8% and 35.1%, respectively). The presence of G allele was associated with 1.69-fold increased risk of preeclampsia (p = 0.005). In severe preeclamptic women, systolic and diastolic blood pressures in the presence of GG+GA genotype were significantly higher compared to those in the presence of AA genotype. The concomitant presence of both alleles of AT2R G and AT1R C was associated with 1.3 times increased risk of mild preeclampsia (p = 0.03). There was an interaction between AT2R G and ACE D alleles that significantly increased the risk of mild and severe preeclampsia by 1.38- and 1.3-fold, respectively. Also, interaction between MMP-9 T and AT2R G alleles increased the risk of severe preeclampsia 1.39-fold (p = 0.028). Our study demonstrated that the G allele of AT2R − 1332 G:A polymorphism is associated with an increased risk of preeclampsia. Also, epistatic interaction of G allele and each allele of the AT1R C, ACE D and MMP-9 T was associated with the risk of preeclampsia. Our findings suggest that the renin–angiotensin system (RAS) variants and gene–gene interactions affect the risk of preeclampsia.     

Association of ANRIL polymorphism (rs1333049:C>G) with myocardial infarction and its pharmacogenomic role in hypercholesterolemia

Single nucleotide polymorphisms (SNPs) of non-coding RNA in the INK4 locus (ANRIL) have been found to be associated with myocardial infarction (MI). However, the effect of rs1333049:C>G in INK4 locus in familial hypercholesterolemia patients and on lipid profile of the patients has not been studied in Pakistan. We therefore investigated the association of SNP rs1333049:C>G with MI as well as familial hypercholesterolemia patients and also determined the effect of genotype on lipid levels in a northern Pakistani population. A case–control association study was performed in which 611 individuals (294 patients, 290 healthy controls and 27 patients from hypercholesterolemia families) were genotyped for rs1333049:C>G, using an Allele specific polymerase chain reaction. We found a significant association of rs1333049:C>G with MI (χ² = 22.3, p < 0.001). The frequency of risk genotype CC was significantly different from the healthy controls (p < 0.001, χ² = 22.3). The risk allele C was at a higher frequency in the MI patients as compared to the controls (odds ratio [OR] = 1.55 (95% confidence interval [CI] = 1.22–1.96), p < 0.001). The logistic regression analysis for the genotype distribution resulted in strong association of risk allele C with MI under recessive model (OR = 3.17 (95% CI = 1.85–5.44) p < 0.001). When the data were further analyzed along the lines of gender, a significant association with both males and females was observed.     

Effect of a GFOD2 variant on responses in total and LDL cholesterol in Mexican subjects with hypercholesterolemia after soy protein and soluble fiber supplementation

Background

Although dietary treatments can successfully reduce blood lipids in hypercholesterolemic subjects, individual variation in that response has on occasion been linked to allelic differences. SNP rs12449157 has shown association with HDL-C concentrations in GWAS and falls in the glucose-fructose oxidoreductase domain containing 2 (GFOD2) locus. Of interest, previous data suggest that this SNP may be under environmentally driven selection. Thus, the aim of this study was to assess if rs12449157 may mediate the response of lipid traits to a dietary supplementation (DS) with soy protein and soluble fiber in a Mexican population with hypercholesterolemia.

Methods

Forty-one subjects with hypercholesterolemia were given a low saturated fat diet (LSFD) for 1 month, followed by a LSFD + DS that included 25 g of soy protein and 15 g of soluble fiber (S/SF) daily for 2 months. Anthropometric, clinical, biochemical and dietary variables were determined. We analyzed the gene–diet interaction between the GFOD2 genotype, with the minor allele frequency of 0.24, and the DS on total cholesterol (TC) and LDL-C concentrations.

Results

Hypercholesterolemic subjects with GFOD2 rs12449157 G allele had higher serum TC and LDL-C at the baseline and showed a greater response to the LSCD + S/SF (− 83.9 and − 57.5 mg/dl, respectively) than those with GFOD2 AA genotype (− 40.1 and − 21.8 mg/dl, respectively) (P = 0.006 for TC, 0.025 for LDL-C, respectively).

Conclusion

The observed differences in allele-driven, diet-induced changes in blood lipids may be the result of a recent environmentally driven selection on the rs12449157 minor allele. Variation in the GFOD2 gene contributes to the genetic basis for a differential response to a cholesterol- or lipid-lowering diet.     

Different effects of PPARA,PPARG and ApoE SNPs on serum lipids in patients with coronary heart disease based on the presence of diabetes

Background

The aim of this study was to investigate the individual or combined effects of PPARA-L162V, PPARG-C161T and APOE polymorphisms on hyperlipidemia in coronary heart disease (CHD) patients.

Methods

Our study included 223 patients with CHD (103 with type 2 diabetes (T2DM), 120 without diabetes) and 101 controls. All genotypes were determined by PCR–RFLP technique.

Results

Genotypic and allelic distributions of PPARA-L162V polymorphism were similar between study and control groups (p > 0.05). The serum total-cholesterol (TC) and LDL-cholesterol (LDL-C) levels were higher in PPARA-V162 allele carriers in non-diabetic CHD patients (p = 0.007 and p = 0.038, respectively). The increasing effect of the PPARA-V162 allele on serum TC and LDL-C levels was weakened with the presence of PPARG-161T allele in the non-diabetic CHD patients. The ApoE4–PPARA-V162 allelic combination of the ApoE/PPARA genes was found to be more frequent in diabetic CHD patients independent of serum lipids (p = 0.035).

Conclusions

The PPARA V162 allele has an increasing effect on TC and LDL-C levels and this effect was reduced by carrying PPARG T161 allele in non-diabetic CHD patients. On the other hand, the V162 allele may be associated with an increased risk of CHD in diabetic CHD patients due to the presence of ApoE4 allele independent of serum lipids. We suggest that the PPARA L162V polymorphism may have diverse effects on serum lipids and CHD risk depends on the presence of T2DM.     

LDL-C calculated by Friedewald,Martin-Hopkins,or NIH equation 2 versus beta-quantification: pooled alirocumab trials

Accurate assessment of LDL-C levels is important, as they are often used for treatment recommendations. For many years, plasma LDL-C levels were calculated using the Friedewald equation, but there are limitations to this method compared with direct measurement via beta-quantification (BQ). Here, we assessed differences between the Friedewald, Martin-Hopkins, and NIH equation 2 methods of calculating LDL-C and the “gold standard” BQ method using pooled phase 3 data with alirocumab. All randomized patients were included irrespective of the treatment arm (n = 6,122). We compared pairs of LDL-C values (n = 17,077) determined by each equation and BQ. We found that BQ-derived LDL-C values ranged from 1 to 397 mg/dl (mean 90.68 mg/dl). There were strong correlations between Friedewald-calculated, Martin-Hopkins–calculated, and NIH equation 2–calculated LDL-C with BQ-determined LDL-C values (Pearson's correlation coefficient = 0.985, 0.981, and 0.985, respectively). Importantly, for BQ-derived LDL-C values ≥70 mg/dl, only 3.2%, 1.4%, and 1.8% of Friedewald-calculated, Martin-Hopkins–calculated, and NIH equation 2–calculated values were <70 mg/dl, respectively. When triglyceride (TG) levels were <150 mg/dl, differences between calculated and BQ-derived LDL-C values were minimal, regardless of the LDL-C level (<40, <55, or <70 mg/dl). However, when TG levels were >150 mg/dl, NIH equation 2 provided greater accuracy than Friedewald or Martin-Hopkins. When TGs were >250 mg/dl, inaccuracies were seen with all three methods, although NIH equation 2 remained the most accurate. In conclusion, LDL-C calculated by any of the three methods can guide treatment decisions for most patients, including those treated with proprotein convertase subtilisin/kexin type 9 inhibitors.