Codon 54 polymorphism of the fatty acid binding protein 2 gene is associated with increased fat oxidation and hyperinsulinemia, but not with intestinal fatty acid absorption in Korean men

Angiotensin-Converting Enzyme Gene D/I Polymorphism in Relation to Endothelial Function and Endothelial-Released Factors in Chinese Women

Many studies have investigated the relationship between angiotensin-converting enzyme (ACE) D/I polymorphism and cardiovascular disease or endothelial dysfunction; however, hardly any of these studies has taken aging or menopause into consideration. Furthermore, despite that many studies have examined the regulatory effects of endothelial-released factors (ERFs) on endothelial function, no study has evaluated the relationship between ERFs and endothelial function with respect to ACE D/I polymorphism and menopause status. To answer these questions, 391 healthy Chinese women over a wide range of ages (22-75 years) were enrolled and divided into pre-menopause group and post-menopause group. After ACE D/I genotype being identified, the women were then classified into either DI/II or DD genotype. Flow-mediated dilatation (FMD) of brachial endothelium and plasma levels of ERFs: nitric oxide (NO), endothelin-1 (ET-1), and angiotensin II (Ang II) were measured. The results showed that frequencies of ACE D/I genotypes were in accordance with the Hardy-Weinberg equilibrium, and the frequency of I allele was higher than D allele. In pre-menopause group, FMD was significantly higher in women of DI/II than DD (P = 0.032), and age-dependent in both genotypes (DD, P = 0.0472; DI/II, P < 0.0001). In post-menopause group, FMD was similar between women of DI/II and DD, and age-dependent only in women of DI/II (P < 0.0001). In pre-menopause group, Ang II level was significantly higher in women of DD than DI/II (P = 0.029), and FMD was significantly correlated with all ERFs in women of DD (NO, P = 0.032; ET-1, P = 0.017; Ang II, P = 0.002), but only with Ang II in women of DI/II (P = 0.026). In post-menopause group, no significant difference was observed in any ERF between women of DI/II and DD, and FMD was only significantly correlated with ET-1 in women of DD (P = 0.010). In summary, FMD in women of DI/II was superior to DD in pre-menopause and more age-dependent than DD in post-menopause, and FMD was closely associated with ERFs. In conclusion, Chinese women of DI/II seem to have lower risk than DD in pre-menopause, but similar risk as DD in post-menopause in developing cardiovascular disease.

Effects of FABP2 Ala54Thr gene polymorphism on obesity and metabolic syndrome in middle-aged Korean women with abdominal obesity

OBJECTIVES

Asians (including Chinese, Japanese and Koreans), who generally have a relatively smaller body size and a lower mean body mass index (BMI), have a relatively higher risk of developing android-type obesity than westerners. Substitution of alanine for threonine (Ala54Thr) on the FABP2 gene (rs 1799883) is related to insulin resistance and obesity. However, few studies have examined this substitution in Koreans, and the number of Korean subjects in those studies is limited. For this reason, we investigated the differences between the FABP2 Ala54Thr polymorphism and obesity, hemodynamic variables, blood lipid profile results, and insulin resistance among middle-aged Korean women with abdominal obesity.

METHODS

We studied 243 middle-aged community-dwelling Korean women with abdominal obesity from Gyeonggi Province, Republic of Korea, who had no history of taking chronic medications. We examined each subject (n = 243) for the presence of FABP2 Ala54Thr polymorphism using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Subjects were also examined for obesity hemodynamic variables (n = 243), lipid profiles (n = 142), and insulin resistance (n = 142).

RESULTS

Of the 243 subjects, 117 had AA ("normal") homozygotic genotype, 100 had AT heterozygotic genotype, and 26 had TT homozygotic genotype for the FABP2 Ala54Thr polymorphism. The AT heterozygotic individuals had a significantly higher mean waist-to-hip ratio, abdominal fat area, and visceral fat area than individuals with other genotypes. TT homozygotic individuals had higher mean triglyceride and fasting glucose levels than individuals with other genotypes.

CONCLUSIONS

The results of this study show that the FABP2 Ala54Thr polymorphism was associated with central obesity and obesity-related metabolic syndrome among middle-aged Korean women.

Angiotensin-converting enzyme insertion/deletion gene polymorphism in Egyptian children with systemic lupus erythematosus: a possible relation to proliferative nephritis

Introduction Angiotensin-converting enzyme (ACE) is crucial in the pathogenesis of systemic lupus erythematosus through angiotensin II which regulates vascular tone and endothelial functions. Objectives To study the frequency of ACE insertion/deletion (I/D) gene polymorphism in Egyptian children with systemic lupus erythematosus and its possible relation to the renal pathology in cases with lupus nephritis. Subjects and methods The frequency of ACE gene insertion/deletion polymorphism genotypes was determined in 78 Egyptian children with systemic lupus erythematosus and compared to a matched group of 140 healthy controls using polymerase chain reaction. Results The DD genotype of the ACE gene was higher in systemic lupus erythematosus patients when compared to controls ( P<0.0001; odds ratio (OR) 2.4; 95% confidence interval (CI) 1.7-3.3) and the D allele was more frequent than the I allele in systemic lupus erythematosus patients in comparison to controls ( P < 0.0001; OR = 2.2; 95% CI = (1.6-3.1). In the lupus nephritis group, the DD genotype was significantly higher in those with proliferative lupus nephritis when compared to those with non-proliferative lupus nephritis ( P = 0.02; OR = 1.45; 95% CI = 1.4-1.6). Also, patients with proliferative lupus nephritis showed a higher frequency of the D allele ( P < 0.001; OR = 1.98; 95% CI = 1.3-2.9). Conclusion The D allele and DD genotype of the ACE gene appear to be a risk factor for the susceptibility of systemic lupus erythematosus and occurrence of proliferative nephritis in Egyptian children.

Association between FABP2 Ala54Thr polymorphisms and type 2 diabetes mellitus risk: a HuGE Review and Meta-Analysis

Many studies have examined the association between the FABP2 (rs1799883) Ala54Thr gene polymorphism and type 2 diabetes mellitus risk (T2DM) in various populations, but their results have been inconsistent. To assess this relationship more precisely, A HuGE review and meta-analysis were performed. The PubMed and CNKI database was searched for case-control studies published up to April 2014. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. Ultimately, 13 studies, comprising 2020 T2DM cases and 2910 controls were included. Overall, for the Thr carriers (Ala/Thr and Thr/Thr) versus the wild-type homozygotes (Ala/Ala), the pooled OR was 1.18 (95% CI = 1.04–1.34, P = 0.062 for heterogeneity), for Thr/Thr versus Ala/Ala the pooled OR was 1.17 (95% CI = 1.05–1.41 P = 0.087 for heterogeneity). In the stratified analysis by ethnicity, the significantly risks were found among Asians but not Caucasians. This meta-analysis suggests that the FABP2 (rs1799883) Ala54Thr polymorphisms are associated with increased susceptibility to T2DM risk among Asians but not Caucasians.

Effects Ala54Thr polymorphism of FABP2 on obesity index and biochemical variable in response to a aerobic exercise training

The purpose of the current study was to investigate whether or not the FABP2 gene polymorphism modulated obesity indices, hemodynamic factor, blood lipid factor, and insulin resistance markers through 12-week aerobic exercise training in abdominal obesity group of Korean mid-life women. A total of 243 abdominally obese subjects of Korean mid-life women voluntarily participated in aerobic exercise training program for 12 weeks. Polymerase Chain Reaction with Restriction Fragment Length Polymorphism (PCR-RFLP) assay was used to assess the FABP2 genotype of the participants (117 of AA homozygotes, 100 of AT heterozygotes, 26 of TT homozygotes). Prior to the participation of the exercise training program, baseline obesity indices, hemodynamic factor, blood lipid factor, and insulin resistance markers were measured. All the measurements were replicated following the 12-week aerobic exercise training program, and then the following results were found. After 12-week aerobic exercise training program, wild type (Ala54Ala) and mutant type (Ala54Thr+Thr54Thr) significantly decreased weight (P > .001), BMI (P > .001), %bf (P > .001), waist circumference (P > .001), WHR (P > .001), muscle mass (wild type p < .022; mutant type P > .001), RHR (P > .001), viseceral adipose area (wild type p < .005; mutant type P > .001), subcutaneous area (P > .001), insulin (wild type p < .005; mutant type P > .001) and significantly increased VO2max (P > .001). And wild type significantly decresed NEFA (P > .05), glucose (P > .05), OGTT 120min glucose (P > .05) and significantly increased HDLC (p > .005). Mutant type significantly decreased SBP (P > .001), DBP (P > .01), TC (P > .01), LPL (P > .05), LDL (P > .001), HOMA index (P > .01). The result of the present study represents that regular aerobic exercise training may beneficially prevent obesity index, blood pressure, blood lipids and insulin resistance markers independent of FABP Ala54Thr wild type and mutant type.

Association of genetic polymorphism of PPARγ-2, ACE, MTHFR, FABP-2 and FTO genes in risk prediction of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a non-autoimmune, complex, heterogeneous and polygenic metabolic disease condition characterized by persistent elevated blood glucose levels (hyperglycemia). India as said to be the diabetic capital of the world is likely to experience the largest increase in T2DM and a greater number of diabetic individuals in the world by the year 2030. Identification of specific genetic variations in a particular ethnic group has a critical role in understanding the risk of developing T2DM in a much efficient way in future. These genetic variations include numerous types of polymorphisms among which single nucleotide polymorphisms (SNPs) is the most frequent. SNPs are basically located within the regulatory elements of several gene sequences. There are scores of genes interacting with various environmental factors affecting various pathways and sometimes even the whole signalling network that cause diseases like T2DM. This review discusses the biomarkers for early risk prediction of T2DM. Such predictions could be used in order to understand the pathogenesis of T2DM and to better diagnostics, treatment, and eventually prevention.

Association of angiotensin-converting enzyme (ACE) and fatty acid binding protein 2 (FABP2) genes polymorphism with type 2 diabetes mellitus in Northern India

BACKGROUND

Type 2 diabetes mellitus (T2DM) is growing in an epidemic manner across the world with an expected doubling of the incidence to millions of affected individuals in the last decades. At present, adequate data are not available regarding the ACE and FABP2 polymorphisms and their susceptibility with T2DM cases in the North Indian population. Thus we conceived the need for further study of ACE (I/D) and FABP2 (Ala54Thr) genes polymorphism and its susceptibility to T2DM in the North Indian population.

MATERIALS AND METHODS

In this study, a total of 300 subjects (including 190 T2DM cases and 110 controls) participated. ACE and FABP2 gene polymorphisms in the cases and controls were evaluated by polymerase chain reaction and restriction fragment length polymorphism.

RESULTS

The frequencies of ACE I/I, I/D and D/D genotypes in T2DM cases and controls were 28.73%, 55.17%, 16.09% and 13.63%, 57.95%, 28.40%, respectively. The frequencies of FABP2 Ala54Ala, Ala54Thr and Thr54Thr in T2DM cases were 18.39%, 66.66%, 14.94% and 22.72%, 61.36%, 15.90% in controls, respectively. ACE I/I genotype was significantly more frequent in cases as compared to controls (p = 0.003, χ(2) = 9.13).

CONCLUSION

It appears that the ACE I/I genotype frequency was significantly higher in the T2DM cases as compared to the controls.

Higher cardiorespiratory fitness attenuates arterial stiffening associated with the Ala54Thr polymorphism in FABP2

Fatty acid binding protein 2 (FABP2) Ala54Thr polymorphism is a candidate gene associated with the risk of cardiovascular disease. Habitual exercise brings higher cardiorespiratory fitness and results in the improvement of cardiovascular disease risk. However, the effect of cardiorespiratory fitness level and FABP2 Ala54Thr polymorphism on the risk of cardiovascular diseases remains unclear. In the present study, a cross-sectional investigation of 837 Japanese men and women was performed to clarify the effects of cardiorespiratory fitness on the relationship between risk of cardiovascular disease and FABP2 Ala54Thr gene polymorphism. The study subjects were divided into high-cardiorespiratory fitness (High-Fit) and low-cardiorespiratory fitness (Low-Fit) groups based on the median value of peak oxygen uptake in each sex and decade. The FABP2 Ala54Thr polymorphism did not significantly affect carotid β-stiffness or blood pressure. In the Low-Fit group, carotid β-stiffness, systolic blood pressure, and diastolic blood pressure were higher for individuals with the Ala/Ala genotype compared with those with the Ala/Thr or Thr/Thr genotype, whereas no differences were observed in the High-Fit group. Additionally, serum triglyceride and plasma glucose levels were lower and serum high-density lipoprotein cholesterol levels were higher in the High-Fit group compared with the Low-Fit group; the FABP2 Ala54Thr polymorphism did not significantly affect these parameters. These results suggest that the higher cardiorespiratory fitness may attenuate the changes in central arterial stiffness and blood pressure that are associated with the FABP2 genotype.

Effects of EPA supplementation on plasma fatty acids composition in hypertriglyceridemic subjects with FABP2 and PPARα genotypes

Background

Fatty acid binding protein 2 (FABP2) and peroxisome proliferator-activated receptor α (PPARα) are involved in cellular uptake and metabolism of fatty acids. Polymorphism of FABP2 and PPARα may influence plasma levels of fatty acids in those who take supplemental eicosapentaenoic acid (EPA). The purpose of this study was to study the potential associations between the Ala54/Thr polymorphism in FABP2 protein and the Leu162/Val in exon 5 and G/C in intron 7 of PPARα with plasma fatty acids composition after EPA supplementation.

Methods

Twenty three FABP2 Ala54 and twenty three Thr54 carriers with hypertriglyceridemia were enrolled in this study. Participants took 2 g of pure EPA daily for 8 wks. Plasma fatty acids composition was determined and changes from the baseline were measured.

Results

Although EPA supplementation increased the level of plasma EPA and ω-3 fatty acids in both carriers of FABP2 and PPARα genes, these effects were more pronounced in Thr54 and Val162 carriers. EPA supplementation decreased the level of some n-6 fatty acids such as arachidonic acid.

Conclusion

EPA consumption has more favorable effects on blood n-3 fatty acids and can change the level of plasma n-3 fatty acids, particularly EPA. Because the FABP2 Thr54 polymorphism appears to be prevalent in hypertriglyceridemic subjects, increasing EPA intake in these subjects could be an effective strategy for preventing cardiovascular diseases. Finally, diets and micronutrient recommendations should be individualized for high risk people.

IntestinalFABP2A54T Polymorphism: Association with Insulin Resistance and Obesity in Women

OBJECTIVE

To assess the association between the Ala54Thr genetic polymorphism of the fatty acid-binding protein 2 (FABP2) gene with insulin resistance and obesity.

RESEARCH METHODS AND PROCEDURES

According to a sampling scheme based on BMI, 33 adult obese women (BMI > or = 30) and 30 adult normal-weight women (BMI > 18.5 and < 25 kg/m(2)) were recruited for this study. Women with chronic inflammatory diseases or acute pathology were excluded. Glucose, insulin, leptin, lipids, and tumor necrosis factor alpha (TNF alpha) were measured in fasting plasma samples. Insulin resistance was estimated through the homeostasis model assessment for insulin resistance method. The Ala54Thr allelic variant was determined by polymerase chain reaction, followed by restriction fragment-length polymorphism analysis.

RESULTS

The Thr54 allele was more frequent in obese than in nonobese women (47.0% vs. 31.7; p = 0.08). Among obese women, higher TNF alpha concentrations were found when comparing the Thr54/Thr54 genotype (30.0 +/- 7.1 pg/mL) with either the Ala54/Thr54 genotype (21.2 +/- 8.4 pg/mL) or the Ala54/Ala44 genotype (20.1 +/- 7.0 pg/mL) (p < 0.05). In addition, higher fasting plasma insulin and leptin levels were found among Thr54/Thr54 homozygotes compared with the other genotypes (p < 0.05).

DISCUSSION

Our results suggest that the Ala54Thr polymorphism of the FABP2 gene is associated with obesity and insulin resistance. The effect of this polymorphism might be mediated by elevated production of TNF alpha.

Meta-analysis on the effect of the Ala54Thr polymorphism of the fatty acid-binding protein 2 gene on body mass index

BACKGROUND AND AIM

The results from studies published on the association of fatty acid-binding protein 2 (FABP2) Ala54Thr polymorphism with body mass index (BMI) are conflicting. In this meta-analysis, we investigated the association of the FABP2 Ala54Thr polymorphism with BMI.

METHODS AND RESULTS

We searched for articles published prior to June 2009 using PubMed, HugeNavigator and China National Knowledge Internet. The languages were limited to English and Chinese. Data on BMI were collected. A pooled weighted mean difference (WMD), together with 95% confidence interval (CI), was used for this meta-analysis. A total of 27 studies with 10 974 subjects were included in this meta-analysis. The pooled effect for dominant, recessive and co-dominant model comparisons did not suggest the significant association between the FABP2 Ala54Thr polymorphism and BMI in overall populations: WMD(fixed effects)=-0.00, 95% CI: (-0.16 to 0.15), p=0.99, WMD(random effects)=-0.00, 95% CI: (-0.16 to 0.15), p=0.99, p(Q)=0.77, I(2)=0%, WMD(fixed effects)=-0.12, 95% CI: (-0.39 to 0.14), p=0.35, WMD(random effects)=-0.12, 95% CI: (-0.39 to 0.14), p=0.35, p(Q)=0.47, I(2)=0% and WMD(fixed effects)=0.07, 95% CI: (-0.11 to 0.25), p=0.45, WMD(random effects)=0.07, 95% CI: (-0.11 to 0.25), p=0.45, p(Q)=0.90, I(2)=0%, respectively. The results from the comparisons of ThrThr versus AlaAla and AlaThr versus AlaAla showed no evidence that the FABP2 Ala54Thr polymorphism is significantly associated with BMI in overall populations (p>0.05). All the results from the subgroup analyses for these genetic models comparisons were not significant (p>0.05).

CONCLUSIONS

Our meta-analysis does not support the association between the FABP2 Ala54Thr polymorphism and BMI.

The human fatty acid-binding protein family: evolutionary divergences and functions

Fatty acid-binding proteins (FABPs) are members of the intracellular lipid-binding protein (iLBP) family and are involved in reversibly binding intracellular hydrophobic ligands and trafficking them throughout cellular compartments, including the peroxisomes, mitochondria, endoplasmic reticulum and nucleus. FABPs are small, structurally conserved cytosolic proteins consisting of a water-filled, interior-binding pocket surrounded by ten anti-parallel beta sheets, forming a beta barrel. At the superior surface, two alpha-helices cap the pocket and are thought to regulate binding. FABPs have broad specificity, including the ability to bind long-chain (C16-C20) fatty acids, eicosanoids, bile salts and peroxisome proliferators. FABPs demonstrate strong evolutionary conservation and are present in a spectrum of species including Drosophila melanogaster, Caenorhabditis elegans, mouse and human. The human genome consists of nine putatively functional protein-coding FABP genes. The most recently identified family member, FABP12, has been less studied.

Metabolic syndrome and ALA54THR polymorphism of fatty acid-binding protein 2 in obese patients

The prevalence of metabolic syndrome (MS) has been estimated to be approximately 25% of the population at large. A transition G to A at codon 54 of fatty acid-binding protein 2 (FABP2) results in an amino acid substitution (ala54 to Thr54), and this polymorphism was associated with some cardiovascular risk factors. The aim of our study was to investigate the relationship between MS and Thr54 polymorphism in the FABP2 gene in obese patients. A population of 750 (body mass index >30) obese patients was analyzed in cross-sectional survey. Bioimpedance, blood pressure, and serial assessment of nutritional intake with 3-day written food records and biochemical analysis were performed. The statistical analysis was performed for the combined Ala54/Thr54 and Thr54/Thr54 as a mutant group and wild-type Ala54/Ala54 as second group. Prevalence of MS with Adult Treatment Panel III definition was 49.7% (373 patients; 24.9% male and 75.1% female), and 50.3% of the patients had no MS (n = 377; 34.2% male and 65.8% female). Prevalence of FABP genotypes was similar in patients with MS (55.5% wild genotype and 44.5% mutant genotype) and without MS (54.6% wild genotype and 45.4% mutant genotype). Prevalence of each criteria of MS was calculated in wild- and mutant-type genotypes, without statistical differences. No differences in anthropometric and biochemical parameters were detected between genotypes in the same group of MS. The finding of our study is the lack of association of the Thr54/Ala54 and Thr54/Thr54 FABP2 genotypes with MS.

Association of the fatty acid-binding protein 2 gene Ala54Thr polymorphism with insulin resistance and blood glucose: a meta-analysis in 13451 subjects

BACKGROUND

The results from the published studies on the association of fatty acid-binding protein 2 (FABP2) Ala54Thr polymorphism with insulin resistance and blood glucose are conflicting. In this meta-analysis, we investigated the association of the FABP2 Ala54Thr polymorphism with insulin resistance and blood glucose.

METHODS

We collected data on fasting blood glucose and fasting insulin, 2-h blood glucose (2-h BG) and 2-h insulin (2-h insulin), and homeostasis model assessment insulin resistance index. A dominant model was used for this meta-analysis.

RESULTS

Thirty-one studies with 13 451 subjects were included in this meta-analysis. The carriers of Thr54 allele have significantly higher homeostasis model assessment insulin resistance index and marginally higher fasting insulin than the non-carriers: standardized mean difference (SMD) = 0.07, 95% confidence interval (CI, 0.02, 0.12), p = 0.007, p(heterogeneity) = 0.19 and SMD = 0.08, 95% CI (-0.01, 0.17), p = 0.07, p(heterogeneity) < 0.00001, respectively. A borderline significant association between the FABP2 Ala54Thr polymorphism and an increased 2-h BG was also detected under the dominant model: SMD = 0.10, 95% CI (0.00, 0.20), p = 0.05, p(heterogeneity) = 0.09. In addition, a borderline association between this polymorphism and an increased fasting blood glucose in populations of other ethnic origins was detected under the dominant model: SMD = 0.11, 95% CI (-0.00, 0.23), p = 0.06, p(heterogeneity) = 0.03.

CONCLUSIONS

Our meta-analysis suggests that the Thr54 allele of the FABP2 Ala54Thr is weakly associated with a higher degree of insulin resistance, higher level of fasting insulin and higher level of 2-h BG. Our meta-analysis also suggests a weak association between this polymorphism and an increased fasting blood glucose in populations of other ethnic origins under the dominant model.

Diet-induced thermogenesis and substrate oxidation are not different between lean and obese women after two different isocaloric meals, one rich in protein and one rich in fat

Reduction in diet-induced thermogenesis (DIT) may promote weight gain and maintenance. Data on differences in DIT and macronutrient oxidation between lean and obese subjects are conflicting. In this study, we sought for differences in DIT and macronutrient oxidation between lean and obese women after consumption of 2 different isocaloric meals, one rich in protein and one rich in fat. Fifteen lean and 15 obese women were studied on 2 occasions, 1 week apart. In one visit, they consumed a protein-rich meal; in the other visit, a fat-rich meal. The 2 meals were isocaloric ( approximately 2026 kJ each), of equal volume, and given in random order. Resting energy expenditure and macronutrient oxidation rates were measured and calculated in the fasting state and every 1 hour for 3 hours after meal consumption. Diet-induced thermogenesis was not significantly different between lean and obese subjects after consumption of either the protein-rich (P = .59) or the fat-rich meal (P = .68). Diet-induced thermogenesis was significantly higher (by almost 3-fold) after consumption of the protein-rich meal in comparison with the fat-rich meal in both study groups. In addition, no significant differences in macronutrient oxidation rates were found between lean and obese women after the test meals. The results indicate that DIT is higher after protein intake than after fat intake in both lean and obese participants; however, DIT and macronutrient oxidation rate are not different between lean and obese subjects after consumption of either a protein-rich or a fat-rich meal. Over the long term, a low DIT after regular or frequent fat intake may contribute to the development and maintenance of obesity.

FABP2 Ala54Thr polymorphism and diabetes in Chilean elders

OBJECTIVE

The FABP2 Ala54Thr polymorphism has been associated with insulin resistance and diabetes in several populations. The aim of this study was to estimate the prevalence of FABP2 genotypes in 223 Chilean subjects (136 women and 87 men aged 65-79 years) and its association with type 2 diabetes in a 4 years follow-up.

METHODS

Glucose, Insulin and lipids were measured in fasting plasma samples. Insulin resistance was estimated through the homeostasis model assessment. Diabetes was diagnosed according ADA criteria. The Ala54Thr allelic variant was determined by polymerase chain reaction and restriction fragment-length polymorphism analysis. Logistic regression techniques were used to assess gene-disease associations.

RESULTS

Genotype frequencies were estimated as 30.5, 49.3 and 20.2% for the Ala/Ala, Ala/Thr and Thr/Thr, respectively. The crude OR for the association between Thr54 carriers and diabetes was estimated as 2.18 (1.12-4.24). The corresponding OR for the association between Thr54 carriers with Metabolic Syndrome was 1.06 (0.59-1.88). After adjustment by BMI and age, a significant association persists for Thr54Thr carriers and diabetes (OR 2.70; 95% CI 1.113-6.527). The 4-year cumulative incidence of diabetes was higher in Thr carriers than in non-carriers (20.1% versus 8.5%; p<0.04). The adjusted association between Thr54Thr polymorphism and diabetes incidence was OR 3.84 (95% CI: 1.140-12.910)

CONCLUSION

Our results strongly suggest an association between the Ala54Thr polymorphism of FABP2 with diabetes, revealing a genetic dosage effect regarding its association with diabetes in Chilean elders.

[Correlation of FABP2-A54T polymorphism and the metabolic syndrome in Maros County of Romania]

OBJECTIVE

The FABP2 (intestinal fatty acid-binding protein) gene is expressed in the intestinal epithelial cells and codes for a protein involved in the fatty acid metabolism. We investigated the association of the A54T polymorphism of the FABP2 gene with the metabolic syndrome defined according to the diagnostic criteria recommended by the IDF in 2005, in our region (Marosvásárhely - Tg. Mures, Romania).

RESEARCH DESIGN AND METHODS

A case-control study was carried out on 144 metabolic syndrome patients and 73 healthy persons with similar age and lifestyle. Insulin resistance was measured by the HOMA and QUICKI indices, and gene polymorphism was analyzed with PCR followed by restriction enzyme digestion with Hha I.

RESULTS

The T54 allele was more frequent in the metabolic syndrome group than in controls (35.71% vs. 28.08%, p < 0.05). In the presence of the T54 allele we have noticed a slight but statistically significant risk, more marked in the case of TT homozygotes (TT vs. AT + AA: OR = 4.31, CI 95% 1.21-5.29, p = 0.015 and TT vs. AA: OR = 4.61, CI95%: 1.24-7.03, p = 0.0195). No significant differences of the followed metabolic parameters were observed between persons having different genotypes in the two study groups.

CONCLUSIONS

These results suggest that the FABP2 T54 allele may have a minor contribution to the metabolic syndrome in our region.

FABP2 Ala54Thr genotype is associated with glucoregulatory function and lipid oxidation after a high-fat meal in sedentary nondiabetic men and women

BACKGROUND

A common functional missense mutation [Ala54Thr of the fatty acid-binding protein 2 gene (FABP2)] has previously been studied for associations with glucoregulation, postprandial lipemia, and lipid oxidation rates. However, most of those studies have not accounted for the interactive and potentially confounding effects of habitual physical activity and diet.

OBJECTIVE

We tested the hypothesis that, in sedentary nondiabetic subjects following a low-fat diet, Thr54 FABP2 carriers have lower glucoregulatory function, greater postprandial lipemia, and greater lipid oxidation rates than do their Ala54 FABP2-homozygous counterparts.

DESIGN

Men and women (n = 122) aged 50-75 y who were following a low-fat diet were genotyped and underwent oral-glucose-tolerance tests. A subgroup (n = 36) also underwent postprandial lipemia tests with lipid oxidation rate measurements.

RESULTS

Thr54 carriers were less likely to have normal glucose tolerance (P = 0.05) and had higher fasting glucose concentrations (P = 0.003) than did Ala54 homozygotes. In Thr54 carriers, the insulin sensitivity index was lower (P = 0.02), and the fasting insulin and the oral-glucose-tolerance test insulin area under the curve were higher (P = 0.05 and 0.03, respectively) than in Ala54 homozygotes. FABP2 genotype was not associated with fasting or postprandial lipemia test triacylglycerol or free fatty acids (P > or = 0.22 for all), but postprandial lipid oxidation rates were higher (P = 0.01), which suggests that fat absorption is higher in Thr54 carriers than in Ala54 homozygotes.

CONCLUSIONS

In sedentary nondiabetic persons following a low-fat diet, FABP2 Thr54 carriers have lower glucose tolerance and lower insulin action than do Ala54-homozygous persons. Furthermore, FABP Thr54 carriers have higher lipid oxidation rates, which may be the mechanism of glucoregulatory dysfunction.

Thr54 allele carriers of the Ala54Thr variant of FABP2 gene have associations with metabolic syndrome and hypertriglyceridemia in urban South Indians

The intestinal fatty acid-binding protein gene is proposed as a candidate gene for diabetes because the protein it codes is involved in fatty acid absorption and metabolism. This study investigates the association of the Ala54Thr variant of the intestinal fatty acid-binding protein gene on type 2 diabetes mellitus and other related metabolic traits in Asian Indians. Ala54Thr polymorphism was genotyped by using polymerase chain reaction-restriction fragment length polymorphism in unrelated 773 type 2 diabetic and 899 normal glucose-tolerant (NGT) subjects, randomly chosen from the Chennai Urban Rural Epidemiology Study, an ongoing population-based study in South India. The Ala54Thr polymorphism was not associated with type 2 diabetes mellitus or obesity. However, genotype-phenotype study revealed that the NGT subjects carrying the Thr54 allele had significantly higher 2-hour plasma glucose (P = .007), glycated hemoglobin (P = .004), 2-hour insulin (P = .027), and fasting low-density lipoprotein cholesterol (P = .032) levels compared with those with the Ala54 allele. Normal glucose-tolerant subjects with Ala54Thr and Thr54Thr genotypes had significantly higher fasting serum triglyceride levels (P = .003) compared with those with Ala54Ala. The subjects were stratified into those with hypertriglyceridemia (serum triglyceride levels >or=150 mg/dL) and those without. The odds ratio for hypertriglyceridemia for the individuals carrying the Ala54Thr genotype was 1.491 (95% confidence interval [CI], 1.22-1.83, P < .0001), and for those carrying the Thr54Thr genotype, it was 1.888 (95% CI, 1.34-2.67; P < .0001). Subjects were also stratified into those with metabolic syndrome (MS) and those without, according to modified Adult Treatment Panel III guidelines. The odds ratio (adjusted for age and sex) for MS for the individuals carrying the Ala54Thr genotype was 1.240 (95% CI, 1.02-1.51; P = .03), whereas for those carrying the Thr54Thr genotype, it was 1.812 (95% CI, 1.28-2.57; P = .001). Carriers of the Thr54 allele have associations with MS and hypertriglyceridemia in this urban South Indian population.

Investigation of Ala54Thr polymorphism in intestinal fatty acid binding protein in Han and Mongoloid populations

AIM: To investigate the single nucleotide polymorphism (SNP) at the 54Ala/Thr (A/T) in the intestinal fatty acid binding protein (IFABP) gene in Hans and Mongolians.

METHODS: Polymerase chain reaction (PCR), restriction endonuclease (HhaI) digestion and DNA sequencing technique were performed to detect the IFABP gene polymorphism at the 54Ala/Thr in 208 Mongolians of pastoral area, 150 Mongolians of Zhangjakou city and 190 Hans.

RESULTS: The allelic frequency of 54Thr was 0.51, 0.33, and 0.30, while that of 54Ala was 0.49, 0.67, and 0.70 in Mongolians of pastoral area, Zhangjakou city and 190 Hans, respectively. In comparison with that of Mongolians in urban area and Hans, the allelic frequency of codon 54Thr in Mongolians of pastoral area was significantly increased (χ² = 22.98, P < 0.01; χ² = 34.23, P < 0.01, respectively), however, it was not significantly different between the Mongolians of urban area and Hans.

CONCLUSION: The IFABP gene polymorphism at 54A/T has no correlation with ethnics among Mongolians and Hans, and the high frequency of 54Thr mutant genotype in Mongolians of pastoral area may be associated with high-fat dieting.

Comparison of the acute response to meals enriched with cis- or trans-fatty acids on glucose and lipids in overweight individuals with differing FABP2 genotypes

Trans-fatty acids have been implicated as a risk factor for cardiovascular disease and diabetes. In addition, a polymorphism at codon 54 (Ala54Thr) in the fatty acid-binding protein 2 (FABP2) gene has been suggested to modify an interaction between dietary fat and insulin sensitivity. We examined the postprandial metabolic profiles after meals enriched with C18:1trans- relative to a similar meal with C18:1cis-fatty acid in individuals who were either FABP2 Ala54 homozygotes or Thr54 carriers. Moderately overweight men and women ate 2 breakfast test meals, separated by 1 week, each providing 40% of their daily energy requirement and containing 50% of energy as fat. In one meal, 10% of energy was from C18:1trans, and in the other meal, the C18:1trans was replaced with C18:1cis. Metabolic parameters were assessed during an 8-hour period. Insulin and C-peptide levels increased more after the C18:1trans meal, and this was associated with a greater fall in free fatty acids. Postprandial glucose levels and oxidation of fatty acids and carbohydrate were not different between the 2 test meals. The Thr54 allele for FABP2 increased the rise in postprandial glucose but not triacylglycerols. Fractional triacylglycerol synthetic rates were higher after consumption of the C18:1trans meal relative to the C18:1cis meal only in Thr54 carriers. These data show that a single meal enriched with C18:1trans-fatty acids can significantly increase insulin resistance, and that in the presence of the FABP2 Thr54 allele, may contribute to increased partitioning of glucose to triacylglycerols and insulin resistance.

Association of the intestinal fatty acid-binding protein Ala54Thr polymorphism and abdominal adipose tissue in African-American and Caucasian women

Genetic variants in the intestinal fatty acid-binding protein-2 (FABP2) gene have been associated with body composition phenotypes. We examined the association between the Ala(54)Thr variant in the FABP2 gene and levels of visceral (VAT) and sc (SAAT) abdominal fat in a group of 223 premenopausal African-American (n = 103) and Caucasian (n = 120) women. Subjects were genotyped for the marker. In addition, body composition was assessed by dual energy x-ray absorptiometry, and VAT was determined from a single computed tomography scan. The frequency of the Thr mutant allele did not differ significantly by ethnic group. After adjusting for total body fat, total abdominal adipose tissue (TAT) and SAAT were significantly lower in carriers of either one or two copies of the mutant Thr allele (P < 0.01). There was no association between total fat mass or VAT and the FABP2 polymorphism. Separate analyses by ethnic group showed that the association between the polymorphism and TAT and SAAT was observed in Caucasian (P < 0.01), but not in African-American (not significant), women. We conclude that women carriers of the FABP2 Thr allele have lower TAT and SAAT than noncarriers of the mutation. This association is present in Caucasian, but not in African-American, women.

Thr54 allele of the FABP2 gene affects resting metabolic rate and visceral obesity

We investigated the relationship between Ala54Thr variant allele of the fatty acid-binding protein 2 (FABP2) gene (Ala54Thr) and development of obesity in Japanese obese women. FABP2 genotypes were determined with a fluorescent allele-specific DNA primer assay system. Body weight, waist and hip circumference, amounts of visceral and subcutaneous white adipose tissue measured by computed tomography (CT) were compared between subjects with Thr allele and without Thr allele before and after the diet and exercise therapy in 80 Japanese obese women. The frequency of the Thr54 allele did not differ between obese and control subjects (0.388 versus 0.329, respectively). In subjects with Ala/Thr and Thr/Thr genotype, adjusted resting metabolic rate (RMR) was significantly lower than the subjects with Ala/Ala genotype. Subjects with the Thr54 allele showed significantly greater waist circumference after diet and exercise therapy than subjects with Ala/Ala genotype. They also demonstrated greater body weight at 20 years of age compared to subjects with Ala/Ala genotype. In conclusion, Thr54 allele of FABP2 has associations with lower adjusted resting metabolic rate, resistance in reducing visceral white adipose tissue (WAT) and early onset of obesity in Japanese obese women.

Variability in energy expenditure and its components

PURPOSE OF REVIEW

To review factors contributing to variation in total daily energy expenditure and its primary components: (1) resting metabolic rate; (2) diet-induced thermogenesis; and (3) activity thermogenesis, including exercise energy expenditure and nonexercise activity. For each component, the expected magnitude of intra-individual variability is also considered. We also reviewed studies that quantified the variability in 24 h energy expenditure.

RECENT FINDINGS

In humans, the coefficient of variation in the components of total daily energy expenditure is around 5-8% for resting metabolic rate, 1-2% for exercise energy expenditure, and around 20% for diet-induced thermogenesis. The coefficient of variance for 24 h energy expenditure measured using a room calorimeter for resting metabolic rate is around 5-10%. Thus, these measures are all rather reproducible. Total daily energy expenditure varies several-fold in humans, not due to variation in resting metabolic rate, diet-induced thermogenesis, or exercise thermogenesis, but rather, due to variations in nonexercise activity. A variety of factors impact nonexercise activity, including occupation, environment, education, genetics, age, gender, and body composition, but little is known about the magnitude of effect.

SUMMARY

Resting metabolic rate, diet-induced thermogenesis, exercise energy expenditure, and 24 h energy expenditure are highly reproducible. Coefficient of variation is smallest for exercise energy expenditure, followed by resting metabolic rate, 24 h energy expenditure, and diet-induced thermogenesis. There is considerable variability in total daily energy expenditure, largely due to variations in nonexercise activity. Although the factors that impact upon nonexercise activity are understood, their contribution to variation in total daily energy expenditure is unclear.

Postprandial lipemia in subjects with the threonine 54 variant of the fatty acid-binding protein 2 gene is dependent on the type of fat ingested

BACKGROUND

The alanine-for-threonine substitution at codon 54 (A54T polymorphism) in the fatty acid-binding protein 2 gene (FABP2) has been associated with hypertriglyceridemia and insulin resistance. Obese and diabetic T54 carriers have greater postprandial lipemia than do A54 homozygotes. The T54 protein isoform is also associated with increased triacylglycerol secretion in vitro.

OBJECTIVE

We investigated diet-gene interactions by measuring postprandial lipids, glucose, insulin, and C-peptide in healthy, nonobese A54 homozygotes and T54 carriers after ingestion of 3 different fats.

DESIGN

Eleven A54 homozygotes and 11 T54 carriers were given 3 oral-fat-tolerance tests (butter, safflower oil, and olive oil). Cholesterol and triacylglycerol were measured in plasma and in chylomicron fractions.

RESULTS

There was no main effect of FABP2 genotype for chylomicron triacylglycerol, glucose, or C-peptide. The area under the insulin curve and the ratio of insulin to C-peptide were lower in T54 carriers than in A54 homozygotes [312 +/- 29 ( +/- SEM) compared with 425 +/- 31 pmol. h/L (P = 0.05) and 0.23 +/- 0.03 compared with 0.40 +/- 0.05 (P = 0.04), respectively], which suggests greater hepatic insulin clearance in T54 carriers. An association between genotype and chylomicron cholesterol was seen only after olive oil: values were higher (P = 0.02) in T54 carriers (0.087 +/- 0.006 mmol. h/L) than in A54 homozygotes (0.058 +/- 0.004 mmol. h/L). The main effect of fat was significant for the areas under the chylomicron cholesterol and chylomicron triacylglycerol curves [higher values for safflower (0.635 +/- 0.053 and 2.48 +/- 0.30 mmol. h/L, respectively) and olive (0.592 +/- 0.052 and 2.48 +/- 0.32 mmol. h/L, respectively) oils than for butter (0.425 +/- 0.043 and 1.69 +/- 0.20 mmol. h/L, respectively); P < 0.05].

CONCLUSIONS

The A54T polymorphism results in a diet-gene interaction: the T54 group had increased chylomicron cholesterol after olive oil only. Nevertheless, the greater hepatic insulin clearance in T54 carriers suggests that the polymorphism may not be deleterious in nonobese subjects.

The A54T polymorphism of fatty acid-binding protein 2 may entail a reduction in fat-stimulated secretion of GIP that potentiates the adverse impact of fatty diets on insulin sensitivity

A common polymorphism of the 54th codon of fatty acid-binding protein 2 (FABP2), in which threonine substitutes for alanine (T54), has been linked to insulin resistance and/or increased postprandial triglycerides in various studies. I propose that, in subjects expressing T54, the secretion of gastric inhibitory polypeptide (GIP) evoked by fatty meals is subnormal, such that adipocytes are less efficient in converting chylomicrons to stored triglyceride. The increased postprandial free fatty acid flux which this may imply could be expected to exacerbate insulin resistance syndrome--thus accounting for the association of T54 with insulin resistance in epidemiological studies. If this thesis proves to be correct, it will help to clarify the importance of appropriate GIP secretion to maintenance of insulin sensitivity in the context of fatty diets.

Fatty acid binding protein-2 gene variants and insulin resistance: gene and gene-environment interaction effects

The intestinal fatty acid binding protein (FABP2) gene is proposed as a candidate gene for diabetes because the protein it codes is involved in fatty acid (FA) absorption and metabolism and may, therefore, affect insulin sensitivity and glucose metabolism. Numerous studies have assessed FABP2 gene variants and their association with insulin resistance and type 2 diabetes. Some weak evidence indicates that the silent variants and those in the noncoding regions of the gene (codon 118, 3' noncoding region, intron 2 trinucleotide repeat) might be associated with insulin resistance/type 2 diabetes. The most extensively studied variant is the missense Ala54Thr variation, which is common in diverse populations and results in increased FA absorption in vivo. Some evidence indicates that this variant may be associated with insulin sensitivity/type 2 diabetes. However, the large majority of studies assessing the potential association between the Ala54Thr FABP2 variant and insulin resistance/type 2 diabetes did not account for the independent and substantial effects of body composition, habitual physical activity (PA) levels, and diet on insulin resistance. We recently reported that there was an association between Ala54Thr FABP2 genotypes and insulin sensitivity after accounting for the independent effects of body composition and habitual PA levels on insulin sensitivity. Furthermore, others have demonstrated that Ala54Thr FABP2 may associate with insulin sensitivity, but only if individuals are consuming a high-fat diet. These results highlight the importance of including behavioral and environmental factors in the design of studies seeking to assess the impact of genes on physiological and clinical outcome phenotypes.

Disordered fat storage and mobilization in the pathogenesis of insulin resistance and type 2 diabetes

The primary genetic, environmental, and metabolic factors responsible for causing insulin resistance and pancreatic beta-cell failure and the precise sequence of events leading to the development of type 2 diabetes are not yet fully understood. Abnormalities of triglyceride storage and lipolysis in insulin-sensitive tissues are an early manifestation of conditions characterized by insulin resistance and are detectable before the development of postprandial or fasting hyperglycemia. Increased free fatty acid (FFA) flux from adipose tissue to nonadipose tissue, resulting from abnormalities of fat metabolism, participates in and amplifies many of the fundamental metabolic derangements that are characteristic of the insulin resistance syndrome and type 2 diabetes. It is also likely to play an important role in the progression from normal glucose tolerance to fasting hyperglycemia and conversion to frank type 2 diabetes in insulin resistant individuals. Adverse metabolic consequences of increased FFA flux, to be discussed in this review, are extremely wide ranging and include, but are not limited to: 1) dyslipidemia and hepatic steatosis, 2) impaired glucose metabolism and insulin sensitivity in muscle and liver, 3) diminished insulin clearance, aggravating peripheral tissue hyperinsulinemia, and 4) impaired pancreatic beta-cell function. The precise biochemical mechanisms whereby fatty acids and cytosolic triglycerides exert their effects remain poorly understood. Recent studies, however, suggest that the sequence of events may be the following: in states of positive net energy balance, triglyceride accumulation in "fat-buffering" adipose tissue is limited by the development of adipose tissue insulin resistance. This results in diversion of energy substrates to nonadipose tissue, which in turn leads to a complex array of metabolic abnormalities characteristic of insulin-resistant states and type 2 diabetes. Recent evidence suggests that some of the biochemical mechanisms whereby glucose and fat exert adverse effects in insulin-sensitive and insulin-producing tissues are shared, thus implicating a diabetogenic role for energy excess as a whole. Although there is now evidence that weight loss through reduction of caloric intake and increase in physical activity can prevent the development of diabetes, it remains an open question as to whether specific modulation of fat metabolism will result in improvement in some or all of the above metabolic derangements or will prevent progression from insulin resistance syndrome to type 2 diabetes.

Cytoplasmic fatty acid-binding proteins: emerging roles in metabolism and atherosclerosis

Cytoplasmic fatty acid-binding proteins (FABPs) are a family of proteins, expressed in a tissue-specific manner, that bind fatty acid ligands and are involved in shuttling fatty acids to cellular compartments, modulating intracellular lipid metabolism, and regulating gene expression. Several members of the FABP family have been shown to have important roles in regulating metabolism and have links to the development of insulin resistance and the metabolic syndrome. Recent studies demonstrate a role for intestinal FABP in the control of dietary fatty acid absorption and chylomicron secretion. Heart FABP is essential for normal myocardial fatty acid oxidation and modulates fatty acid uptake in skeletal muscle. Liver FABP is directly involved in fatty acid ligand signaling to the nucleus and interacts with peroxisome proliferator-activated receptors in hepatocytes. The adipocyte FABP (aP2) has been shown to affect insulin sensitivity, lipid metabolism and lipolysis, and has recently been shown to play an important role in atherosclerosis. Interestingly, expression of aP2 by the macrophage promotes atherogenesis, thus providing a link between insulin resistance, intracellular fatty acid disposition, and foam cell formation. The FABPs are promising targets for the treatment of dyslipidemia, insulin resistance, and atherosclerosis in humans.