An analysis of peroxisome proliferator-activated receptor gamma (PPAR-gamma 2) Pro12Ala polymorphism distribution and prevalence of type 2 diabetes mellitus (T2DM) in world populations in relation to dietary habits

The Combined Effect of Polygenic Risk from FTO and ADRB2 Gene Variants, Odds of Obesity, and Post-Hipcref Diet Differences

BACKGROUND

Computing polygenic risk scores (PRS) to predict the degree of risk for obesity may contribute to weight management programs strategically.

OBJECTIVES

To investigate the combined effect of FTO rs9930501, rs9930506, and rs9932754 and ADRB2 rs1042713 and rs1042714 using PRS on (1) the odds of obesity and (2) post-intervention differences in dietary, anthropometric, and cardiometabolic parameters in response to high-protein calorie-restricted, high-vitamin E, high-fiber (Hipcref) diet intervention in Malaysian adults.

METHODS

Both a cross-sectional study (n = 178) and a randomized controlled trial (RCT) (n = 128) were conducted to test the aforementioned objectives. PRS was computed as the weighted sum of the risk alleles possessed by each individual participant. Participants were stratified into first (PRS 0-0.64), second (PRS 0.65-3.59), and third (PRS 3.60-8.18) tertiles.

RESULTS

The third tertile of PRS was associated with significantly higher odds of obesity: 2.29 (95% CI = 1.11-4.72, adjusted p = 0.025) compared to the first tertile. Indians (3.9 ± 0.3) had significantly higher PRS compared to Chinese (2.1 ± 0.4) (p = 0.010). In the RCT, a greater reduction in high-sensitivity C-reactive protein (hsCRP) levels was found in second and third tertiles after Hipcref diet intervention compared to the control diet (p interaction = 0.048).

CONCLUSION

Higher PRS was significantly associated with increased odds of obesity. Individuals with higher PRS had a significantly greater reduction in hsCRP levels after Hipcref diet compared to the control diet.

Genetic polymorphisms of PPAR genes and human cancers: evidence for gene-environment interactions

Peroxisome proliferator-activated receptors (PPARs) are nuclear transcription factors that play a role in lipid metabolism, cell proliferation, terminal differentiation, apoptosis, and inflammation. Although several cancer models have been suggested to explain PPARs' involvement in tumorigenesis, however, their role is still unclear. In this review, we examined associations of the different PPARs, polymorphisms and various types of cancer with a focus on gene-environment interactions. Reviewed evidence suggests that functional genetic variants of the different PPARs may modulate the relationship between environmental exposure and cancer risk. In addition, this report unveils the scarcity of reliable quantitative environmental exposure data when examining these interactions, and the current gaps in studying gene-environment interactions in many types of cancer, particularly colorectal, prostate, and bladder cancers.

Assessment of the Pro12Ala Polymorphism in the PPAR-γ2 Gene among Type 2 Diabetes Patients in a Nigerian Population

The association between the Pro12Ala polymorphism of the PPARγ2 gene, type 2 diabetes (T2D), and obesity in certain ethnic populations has been reported. However, this relationship has not yet been described among diabetes patients in Nigeria. This study investigated the relationship between the Pro12Ala polymorphism in the PPARγ2 gene, obesity, and lipid abnormalities characterizing T2D among patients in Nigeria. This case-control study recruited 73 T2D and 75 non-diabetic (ND) patients. Demographic and clinical data were collected and blood glucose levels together with serum lipid profile for patients were measured. Pro12Ala polymorphism in the PPARγ2 gene was genotyped by restriction fragment length-Polymerase Chain Reaction (RFLP-PCR). The PPAR-γ2 gene (amplicon size = 270 base pair) was successfully amplified for all samples. Following restriction enzyme digestion and analysis by agarose gel electrophoresis, amplicons from samples showed a band of size 270 bp and were of the wild homozygous Pro/Pro genotype. Ala12 variant was totally absent from the study population. Obesity, estimated using Body Mass Index (BMI) and waist circumference (WC), was significantly higher (p < 0.05) in T2D patients compared to the non-diabetic patients. More so, the prevalence of lipid abnormalities; hypercholesterolaemia (TC > 200 mg/dL), hypertriglyceridaemia (TG > 150 mg/dL), high HDL (>100 mg/dL), and low HDL (<50 mg/dL) was significantly greater (p < 0.001) in T2D patients compared to non-diabetic patients. Results obtained further indicated lack of significant association between PPAR-γ2 gene polymorphism, T2D, and obesity. However, obesity and dyslipidaemia were strongly associated in T2D patients.

High genetic risk scores for impaired insulin secretory capacity doubles the risk for type 2 diabetes in Asians and is exacerbated by Western-type diets

BACKGROUND

Asians have among the highest incidence of type 2 diabetes (T2DM) in the world, partly due to low β-cell function, causing them to rapidly develop T2DM when insulin resistant. This study tested the hypothesis that genetic polymorphisms are responsible for the low β-cell function and that dietary factors interact with the genes to exacerbate their risk of T2DM.

METHODS

We selected 10 genetic variants of 5 genes involved in insulin secretion (CDKAL1, KCNQ1, IDE, HHEX, and ABCA1) from the genome-wide association studies to calculate the genetic risk scores (GRSs) in 8842 Korean adults in the Ansan/Ansung cohort in the Korean Genome Epidemiology Study. The genetic risk score were divided into low, medium, and high groups, and the association between T2DM and the genetic risk score was measured using logistic regression. We also analysed the interaction between the genetic risk score and the nutrition intakes.

RESULTS

The individual genetic variants were positively associated with T2DM even when adjusted for covariates. Individuals with medium and high genetic risk score had higher T2DM risk by 1.68 and 2.17 folds compared to those with the low genetic risk score after adjusting for covariates. The increased risk was mainly associated with lower HOMA-B, an indicator of insulin secretion capacity, but not HOMA-IR, an indicator of insulin resistance. Subjects with high carbohydrate intakes and a medium genetic risk score did not have a higher risk of T2DM, and the risk was partially mitigated in the high genetic risk score group.

CONCLUSION

Seventy-two percent of the Korean population had either medium or high genetic risk scores for impaired insulin secretion, which approximately doubled their risk of type 2 diabetes, and the risk was exacerbated by consuming a low carbohydrate Western-style diets.

Association of polymorphisms of peroxisome proliferator activated receptors in early and late onset of type 2 diabetes mellitus

OBJECTIVE

Genetic variation of disease susceptible genes is different in different ethnic groups and there is an evidence of association of polymorphisms of Peroxisome Proliferator Activated Receptors (PPARs) in Type 2 Diabetes Mellitus (T2DM). This research analyses the association of PPARs in early and late onset of T2DM in North Indian Population (NIP).

METHODS

Total of 703 subjects were recruited from north of India and subjects were further divided into subjects of early onset (less than 25 years of onset, 26 T2DM and 26 controls) and late onset (more than 25 years of onset, 326 T2DM and 325 controls).

RESULT

The onset of T2DM begins from 15 years and continues further to maximum T2DM subjects to the age of 50 (76% of T2DM). High BMI and WHR, high blood pressure leading to early onset of hypertension, early mortality due to T2DM (7% of T2DM is above 75 years and 3% of T2DM has 20 years duration of onset) and high hyperglycemic NIP were the few outcomes of this research.

CONCLUSION

There is a strong association of PPAR γ, PPAR α and PPAR δ genes on the susceptibility of T2DM in late onset but not with the early onset of T2DM subjects in North Indian Population: Dual association of PPAR γ was observed with its genotype G/G (Ala/Ala) favoring protection against T2DM and genotype C/C (Pro/Pro) favoring susceptibility to T2DM. Association of intron7 polymorphism of PPAR α and +T294C polymorphism of PPAR δ on the susceptibility to T2DM requires further analysis.

Metabolomic analysis of insulin resistance across different mouse strains and diets

Insulin resistance is a major risk factor for many diseases. However, its underlying mechanism remains unclear in part because it is triggered by a complex relationship between multiple factors, including genes and the environment. Here, we used metabolomics combined with computational methods to identify factors that classified insulin resistance across individual mice derived from three different mouse strains fed two different diets. Three inbred ILSXISS strains were fed high-fat or chow diets and subjected to metabolic phenotyping and metabolomics analysis of skeletal muscle. There was significant metabolic heterogeneity between strains, diets, and individual animals. Distinct metabolites were changed with insulin resistance, diet, and between strains. Computational analysis revealed 113 metabolites that were correlated with metabolic phenotypes. Using these 113 metabolites, combined with machine learning to segregate mice based on insulin sensitivity, we identified C22:1-CoA, C2-carnitine, and C16-ceramide as the best classifiers. Strikingly, when these three metabolites were combined into one signature, they classified mice based on insulin sensitivity more accurately than each metabolite on its own or other published metabolic signatures. Furthermore, C22:1-CoA was 2.3-fold higher in insulin-resistant mice and correlated significantly with insulin resistance. We have identified a metabolomic signature composed of three functionally unrelated metabolites that accurately predicts whole-body insulin sensitivity across three mouse strains. These data indicate the power of simultaneous analysis of individual, genetic, and environmental variance in mice for identifying novel factors that accurately predict metabolic phenotypes like whole-body insulin sensitivity.

The Genetic Predisposition Score of Seven Obesity-Related Single Nucleotide Polymorphisms Is Associated with Better Metabolic Outcomes after Roux-en-Y Gastric Bypass

BACKGROUND/AIMS

Genetic variants associated with obesity have cumulative effects on obesity risk and related phenotypes. This study aimed to estimate the contribution of a genetic predisposition score (GPS) calculated from 7 obesity-related polymorphisms to the improvement of biochemical parameters 1 year after Roux-en-Y gastric bypass (RYGB).

METHODS

Obese patients (n = 150; aged 47.2 ± 10.5 years) were enrolled and weight, body mass index (BMI), and biochemical parameters (glycemia and lipid profile) were evaluated preoperatively and 1 year after RYGB. A GPS was calculated with the polymorphisms rs1801282 of PPARG2, rs4994 of ADRB3, rs1800592 of UCP1, rs659366 and rs669339 of UCP2, rs7121 of GNAS1, and rs5443 of GNB3. We observed that 66.3% of the patients has a GPS >5.

RESULTS

During the preoperative period, the GPS showed a significant association with weight (β = -0.163; p = 0.020), BMI (β = -0.169; p = 0.038), and glucose concentrations (β = -0.177; p = 0.036). After sex and age adjustment, a higher GPS was associated with a greater reduction in glycemia (β = -0.158; p = 0.048), triglycerides (β = -0.256; p = 0.002), and total cholesterol (β = -0.172; p = 0.038) concentrations 1 year after surgery.

CONCLUSION

Our data elucidated that a higher GPS provides a greater metabolic benefit of RYGB.

The Pro12Ala polymorphism in the PPAR-γ2 gene is not associated to obesity and type 2 diabetes mellitus in a Cameroonian population

Background

Peroxisome proliferator-activated receptor gamma 2 (PPAR-γ2) is a transcription factor with a key role in adipocyte differentiation, lipid storage and glucose homeostasis. The Ala allele of the common Pro12Ala polymorphism in the isoform PPAR-γ2 is at the center of many controversies because in some populations, it has been observed to be associated with T2DM or obesity but, not in others. The aim of this study was to investigate the association of Pro12Ala polymorphism in the PPAR-γ2 gene with susceptibility to obesity or T2DM in a Cameroonian population.

Methods

This case-control study included 62 obese, 60 T2DM patients and 120 controls (60 non obese and 60 patients without T2DM), all unrelated and of Cameroonian origin. PPAR-γ2 was examined by genotyping for Pro12Ala using the Restriction Fragment Length Polymorphism - Polymerase Chain Reaction (PCR - RFLP).

Results

A portion of the 270 base pair bands of the PPAR-γ2 gene was successfully amplified. The Ala12 variant was totally absent from the study population, all participants being homozygote Pro/Pro.

Conclusion

PPAR-γ2 Pro12Ala gene polymorphism may not be associated with obesity and T2DM. These results suggest that, PPAR-γ2 is unlikely a major gene for obesity or T2DM in the study population.

Genetic epidemiology of type 2 diabetes and cardiovascular diseases in Africa

The burdens of type 2 diabetes (T2D) and cardiovascular diseases (CVD) are increasing in Africa. T2D and CVD are the result of the complex interaction between inherited characteristics, lifestyle, and environmental factors. The epidemic of obesity is largely behind the exploding global incidence of T2D. However, not all obese individuals develop diabetes and positive family history is a powerful risk factor for diabetes and CVD. Recent implementations of high throughput genotyping and sequencing approaches have advanced our understanding of the genetic basis of diabetes and CVD by identifying several genomic loci that were not previously linked to the pathobiology of these diseases. However, African populations have not been adequately represented in these global genomic efforts. Here, we summarize the state of knowledge of the genetic epidemiology of T2D and CVD in Africa and highlight new genomic initiatives that promise to inform disease etiology, public health and clinical medicine in Africa.

The TCF7L2 rs7903146 (T) allele is associated with type 2 diabetes in urban Ghana: a hospital-based case-control study

Background

Type 2 diabetes mellitus is increasing dramatically in sub-Saharan Africa, and genetic predisposition is likely involved in that. Yet, genetic variants known to confer increased susceptibility among Caucasians are far from being established in African populations. In Ghanaian adults, we examined associations of several of these polymorphisms with type 2 diabetes.

Methods

A hospital-based case–control study on type 2 diabetes (and hypertension) was conducted in Kumasi, Ghana. TCF7L2 rs7903146, KCNJ11 rs5219, PPARγ rs1801282 and CAPN10 rs3842570, rs3792267, and rs5030952 were typed and associations with type 2 diabetes and phenotypic traits examined.

Results

675 patients with type 2 diabetes and 377 controls were compared. The minor allele frequency of the TCF7L2 (T) allele was 0.33. In the multivariate model, this allele increased the risk of type 2 diabetes by 39% (95% confidence interval (CI), 1.07-1.81; p = 0.014). The minor alleles KCNJ11 (G) and PPARγ (G) were practically absent (each, 0.001). Minor allele frequencies of CAPN10 were for -43 (A) 0.11 and for -63 (C) 0.46. These variants showed no significant associations with type 2 diabetes. Two CAPN10 haplotypes tended to protect against type 2 diabetes: 211 (aOR, 0.32; 95% CI, 0.03-1.92; p = 0.31) and 221 (aOR, 0.73; 95% CI, 0.48-1.10; p = 0.13).

Conclusions

In urban Ghana, the frequency of the TCF7L2 rs7903146 (T) allele is comparable to the one in Caucasians; the association with type 2 diabetes is slightly weaker. The risk allele KCNJ11 (G) and the protective allele PPARγ (G) are virtually absent. The potential influence of comparatively rare CAPN10 haplotypes on type 2 diabetes risk in this population requires further evaluation. Large-scale genetic studies among native Africans aiming at fine-mapping the candidate genes are needed to identify the actual factors involved in their increased susceptibility to type 2 diabetes.

Association between PRO12ALA polymorphism of the PPAR-γ2 gene and type 2 diabetes mellitus in Iranian patients

BACKGROUND:

Peroxisome proliferator-activated receptor (PPARs) have been identified as ligand-activated transcription factors that belong to the nuclear receptor superfamily. It has been shown that an association exists between Proline 12 alanine (Pro12Ala) polymorphism of PPAR-GAMMA2 (PPAR-γ2) gene and increased risk of type 2 diabetes mellitus (T2DM) in different populations. Therefore, the present study was designed to investigate the association between Pro12Ala polymorphism of PPAR-γ2 gene and T2DM in an Iranian population.

MATERIALS AND METHODS:

Two hundred unrelated people, including 100 healthy controls and 100 diabetic patients were recruited diagnosed based on American Diabetes Association criteria. Blood samples were used for isolation of genomic deoxyribonucleic acid (DNA). Having extracted the genomic DNA from human blood leukocytes by means of High Pure polymerase chain reaction (PCR) Template preparation kit, we carried out polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) on each blood sample. Then, Genomic DNA was digested by BstU-I restriction enzyme. Thereafter, restriction products were analyzed by means of Polyacrylamide gel electrophoresis and stained by Ethidium Bromide.

RESULTS:

We found that the frequency of Ala allele in healthy subjects was significantly higher than in diabetic subjects (P = 0003). Moreover, the genotype frequency of Ala/Ala in healthy subjects was significantly higher than in diabetic subjects (P < 0.001). However, the genotype frequency of Ala/Pro in diabetic subjects was significantly higher than in healthy subjects (P < 0.001).

CONCLUSION:

The present study suggests that polymorphism of PPAR-γ2 gene is associated with T2DM. Furthermore, Ala allele is significantly found in non-diabetic individual’s Iranian population.

ACE I/D and MTHFR C677T polymorphisms are significantly associated with type 2 diabetes in Arab ethnicity: a meta-analysis

In this meta-analysis study, SNPs were investigated for their association with type 2 diabetes (T2D) in both Arab and Caucasian ethnicities. A total of 55 SNPs were analyzed, of which 11 fulfilled the selection criteria, and were used for analysis. It was found that TCF7L2 rs7903146 was significantly associated with a pooled OR of 1.155 (95%C.I.=1.059-1.259), p<0.0001 and I(2)=78.30% among the Arab population, whereas among Caucasians, the pooled OR was 1.45 (95%C.I.=1.386-1.516), p<0.0001 and I(2)=77.20%. KCNJ11 rs5219 was significantly associated in both the populations with a pooled OR of 1.176(1.092-1.268), p<0.0001 and I(2)=32.40% in Caucasians and a pooled OR of 1.28(1.111-1.475), p=0.001 among Arabs. The ACE I/D polymorphism was found to be significantly associated with a pooled OR of 1.992 (95%C.I.=1.774-2.236), p<0.0001 and I(2)=83.20% among the Arab population, whereas among Caucasians, the pooled OR was 1.078 (95%C.I.=0.993-1.17), p=0.073 and I(2)=0%. Similarly, MTHFR C677T polymorphism was also found to be significantly associated among Arabs with a pooled OR of 1.924 (95%C.I.=1.606-2.304), p<0.0001 and I(2)=27.20%, whereas among Caucasians, the pooled OR was 0.986 (95%C.I.=0.868-1.122), p=0.835 and I(2)=0%. Meanwhile PPARG-2 Pro12Ala, CDKN2A/2B rs10811661, IGF2BP2 rs4402960, HHEX rs7923837, CDKAL1 rs7754840, EXT2 rs1113132 and SLC30A8 rs13266634 were found to have no significant association with T2D among Arabs. In conclusion, it seems from this study that both Arabs and Caucasians have different SNPs associated with T2D. Moreover, this study sheds light on the profound necessity for further investigations addressing the question of the genetic components of T2D in Arabs.

Nutrigenetics and metabolic disease: current status and implications for personalised nutrition

Obesity, particularly central adiposity, is the primary causal factor in the development of insulin resistance, the hallmark of the metabolic syndrome (MetS), a common condition characterized by dyslipidaemia and hypertension, which is associated with increased risk of cardiovascular disease (CVD) and type 2 diabetes (T2DM). Interactions between genetic and environmental factors such as diet and lifestyle, particularly over-nutrition and sedentary behavior, promote the progression and pathogenesis of these polygenic diet-related diseases. Their current prevalence is increasing dramatically to epidemic proportions. Nutrition is probably the most important environmental factor that modulates expression of genes involved in metabolic pathways and the variety of phenotypes associated with obesity, the MetS and T2DM. Furthermore, the health effects of nutrients may be modulated by genetic variants. Nutrigenomics and nutrigenetics require an understanding of nutrition, genetics, biochemistry and a range of “omic” technologies to investigate the complex interaction between genetic and environmental factors relevant to metabolic health and disease. These rapidly developing fields of nutritional science hold much promise in improving nutrition for optimal personal and public health. This review presents the current state of the art in nutrigenetic research illustrating the significance of gene-nutrient interactions in the context of metabolic disease.

PPARγ Pro12Ala and ACE ID polymorphisms are associated with BMI and fat distribution, but not metabolic syndrome

Background

Metabolic Syndrome (MetS) results from the combined effect of environmental and genetic factors. We investigated the possible association of peroxisome proliferator-activated receptor-γ2 (PPARγ2) Pro12Ala and Angiotensin Converting Enzyme (ACE) I/D polymorphisms with MetS and interaction between these genetic variants.

Methods

Three hundred sixty four unrelated Caucasian subjects were enrolled. Waist circumference, blood pressure, and body mass index (BMI) were recorded. Body composition was estimated by impedance analysis; MetS was diagnosed by the NCEP-ATPIII criteria. A fasting blood sample was obtained for glucose, insulin, lipid profile determination, and DNA isolation for genotyping.

Results

The prevalence of MetS did not differ across PPARγ2 or ACE polymorphisms. Carriers of PPARγ2 Ala allele had higher BMI and fat-mass but lower systolic blood pressure compared with Pro/Pro homozygotes. A significant PPARγ2 gene-gender interaction was observed in the modulation of BMI, fat mass, and blood pressure, with significant associations found in women only. A PPARγ2-ACE risk genotype combination for BMI and fat mass was found, with ACE DD/PPARγ2 Ala subjects having a higher BMI (p = 0.002) and Fat Mass (p = 0.002). Pro12Ala was independently associated with waist circumference independent of BMI and gender.

Conclusions

Carriers of PPARγ2 Ala allele had higher BMI and fat-mass but not a worse metabolic profile, possibly because of a more favorable adipose tissue distribution. A gene interaction exists between Pro12Ala and ACE I/D on BMI and fat mass. Further studies are needed to assess the contribution of Pro12Ala polymorphism in adiposity distribution.

An age-dependent diet-modified effect of the PPARγ Pro12Ala polymorphism in children

Variation in the peroxisome proliferator-activated receptor γ gene alters the risk for adiposity in adults, with evidence of interaction with diet. We investigated the age-related association between the Pro12Ala variant (rs1801282) and diet in obesity-related traits in children. The Pro12Ala variant was assayed in 2102 young children aged 1 to 6 years and in 794 periadolescent children aged 10 to 12 years of Greek origin. In both cohorts, no differences were found in obesity traits between the Ala allele carriers and Pro/Pro homozygotes. Sex-stratified analysis showed that, in periadolescent boys, Ala carriers exhibited lower measures of skinfolds (triceps: 16.9 ± 6.9 vs 19.4 ± 7.9 mm, P = .01; subscapular: 9.6 ± 4.5 vs 11.2 ± 5.4 mm, P = .02). On the other hand, young girls who were Ala carriers presented higher measures of triceps skinfold thickness (10.5 ± 3.0 vs 9.9 ± 2.8 mm, P = .04). Nominal gene-diet interactions were revealed in periadolescents for saturated fatty acid (SFA) intake and skinfolds (P for interaction = .05). In Pro/Pro homozygous young girls, SFA and total fat (TF) intake was positively associated with higher body mass index (BMI) (P = .01), waist circumference (P = .02), and skinfold thickness (triceps-SFA: P = 10⁻⁵, triceps-TF: P = 10⁻⁹, subscapular-SFA: P = 10⁻⁶, subscapular-TF: P = 10⁻⁴). For Pro/Pro homozygotes, unsaturated fat intake was inversely associated with BMI (P = .04) in young girls, and with BMI (P = .03), waist circumference (P = .03), and triceps (P = .02) in periadolescent boys. Our results suggest that adiposity in children is influenced by the Pro12Ala polymorphism in a sex-specific and age-dependent manner. We also demonstrate evidence of an age-dependent gene-diet (SFA, TF) interaction, suggesting that the type of fat intake modifies the effect of the Pro12 allele on obesity-related measures.

Anti-diabetic effects including diabetic nephropathy of anti-osteoporotic trace minerals on diabetic mice

OBJECTIVE

In our previous study to evaluate the effects of soluble silicon (Si) on bone metabolism, Si and coral sand (CS) as a natural Si-containing material suppressed peroxisome proliferator-activated receptor γ (PPARγ), which regulates both glucose and bone metabolism and increases adipogenesis at the expense of osteogenesis, leading to bone loss. In this study, we investigated the anti-diabetic effects of bone-seeking elements, Si and stable strontium (Sr), and CS as a natural material containing these elements using obese diabetic KKAy mice.

METHODS

Weanling male mice were fed diets containing 1% Ca supplemented with CaCO(3) as the control and CS, and diets supplemented with 50 ppm Si or 750 ppm Sr to control diet for 56 d. The mRNA expressions related to energy expenditure in the pancreas and kidney were quantified by real-time polymerase chain reaction.

RESULTS

At the end of feeding, plasma glucose, insulin, leptin, and adiponectin levels decreased significantly in three test groups, while pancreatic PPARγ and adiponectin mRNA expression levels increased significantly toward the normal level, improving the glucose sensitivity of β-cells and inducing a significant decrease in insulin expression. The renal PPARγ, PPARα, and adiponectin expression levels, histologic indices of diabetic glomerulopathy, and plasma indices of renal function were also improved significantly in the test groups.

CONCLUSION

Taken together, anti-osteoporotic trace minerals, Si and Sr, and CS containing them showed novel anti-diabetic effects of lowering blood glucose level, improving the tolerance to insulin, leptin, and adiponectin, and reducing the risk of glomerulopathy through modulation of related gene expression in the pancreas and kidney.

PPARγ2 polymorphism and human health

The nuclear hormone receptor peroxisome proliferator activated receptor gamma (PPARγ) is an important transcription factor regulating adipocyte differentiation, lipid and glucose homeostasis, and insulin sensitivity. Numerous genetic mutations of PPARγ have been identified and these mutations positively or negatively regulate insulin sensitivity. Among these, a relatively common polymorphism of PPARγ, Pro12Ala of PPARγ2, the isoform expressed only in adipose tissue has been shown to be associated with lower body mass index, enhanced insulin sensitivity, and resistance to the risk of type 2 diabetes in human subjects carrying this mutation. Subsequent studies in different ethnic populations, however, have revealed conflicting results, suggesting a complex interaction between the PPARγ2 Pro12Ala polymorphism and environmental factors such as the ratio of dietary unsaturated fatty acids to saturated fatty acids and/or between the PPARγ2 Pro12Ala polymorphism and genetic factors such as polymorphic mutations in other genes. In addition, this polymorphic mutation in PPARγ2 is associated with other aspects of human diseases, including cancers, polycystic ovary syndrome, Alzheimer disease and aging. This review will highlight findings from recent studies.

The Pro12Ala polymorphism of the PPARG gene is not associated with the metabolic syndrome in an urban population of middle-aged Swedish individuals

BACKGROUND

To determine if the common Pro12Ala polymorphism (rs1801282) of the peroxisome proliferator-activated receptor (PPARG) gene is associated with the metabolic syndrome (MetS) or with its individual components in middle-aged Swedish individuals.

METHODS

MetS was defined according to the National Cholesterol Education Program/Adult Panel III (NCEP/ATP III), the International Diabetes Federation (IDF) and the European Group for the Study of Insulin Resistance (EGIR) criteria in a population-based sample of nearly 5000 subjects participating in the Malmö Diet and Cancer-cardiovascular arm.

RESULTS

Of the subjects included in the analysis, 21.8, 29.4 and 20.4% had MetS according to the NCEP/ATP III, IDF and EGIR (only in subjects without diabetes) definitions, respectively. The Pro12Ala was not associated with MetS or with its individual components. These results were similar when patients with diabetes were excluded. Hypertensive and obese ala-carriers had lower fasting glucose and hypertensive ala-carriers also had lower level triglycerides (P < 0.05).

CONCLUSIONS

Our data do not support a major role for the Pro12Ala variant of the PPARG gene in MetS and its individual components. The modest difference in triglyceride and glucose levels, restricted to hypertensive and obese subjects in our cohort, suggests that the polymorphism has a minor effect on glucose and lipid metabolism, particularly in individuals at risk for gluco-metabolic disturbances.

Study on a possible effect of four longevity candidate genes (ACE, PON1, PPAR-gamma, and APOE) on human fertility

The present study investigated for a possible effect on fertility of four longevity candidate genes (ACE, PON1, PPAR-gamma, APOE) in order to determine whether they have a pleiotropic action at different life ages. The study population was 151 healthy unrelated subjects. Only PPAR-gamma and APOE showed an effect on fertility. The PPAR-gamma Pro/Ala genotype, which had showed an association with longevity only in men, was found associated only in men with having produced more children (6.1+/-3.3) than the Pro/Pro genotype (3.3+/-1.9; P=0.001). APOE*2 allele, which has been consistently associated with longevity, was confirmed to be associated with the lowest fertility (P=0.03). The logistic regression analysis indicated that APOE and PPAR-gamma polymorphisms may be considered independent determinants of reproductive efficiency. These data suggest that the APOE*2 allele follows the model of antagonist pleiotropy, while the PPAR-gamma Pro/Ala genotype seems to exert beneficial effects both early in life and in advanced age in a gender-specific way.

Why study gene-environment interactions?

PURPOSE OF REVIEW

We examine the reasons for investigating gene-environment interactions and address recent reports evaluating interactions between genes and environmental modulators in relation to cardiovascular disease and its common risk factors.

RECENT FINDINGS

Studies focusing on smoking, physical activity, and alcohol and coffee consumption are observational and include relatively large sample sizes. They tend to examine single genes, however, and fail to address interactions with other genes and other correlated environmental factors. Studies examining gene-diet interactions include both observational and interventional designs. These studies are smaller, especially those including dietary interventions. Among the reported gene-diet interactions, it is important to highlight the strengthened position of APOA5 as a major gene that is involved in triglyceride metabolism and modulated by dietary factors, and the identification of APOA2 as a modulator of food intake and obesity risk.

SUMMARY

The study of gene-environment interactions is an active and much needed area of research. Although technical barriers of genetic studies are rapidly being overcome, inclusion of comprehensive and reliable environmental information represents a significant shortcoming of genetics studies. Progress in this area requires inclusion of larger populations but also more comprehensive, standardized, and precise approaches to capturing environmental information.