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Uncoupling protein 2 promoter polymorphism -866G/A, central adiposity, and metabolic syndrome in Asians

Shen H, Qi L, Tai ES, Chew SK, Tan CE, Ordovas JM

Obesity (Silver Spring), 2006 Apr;14(4):656-61.
PMID: 16741267

A polymorphism in the promoter region of uncoupling protein 2 gene -866G/A has been associated with its expression levels in adipose tissue, the risk of obesity, and metabolic abnormalities. Our purpose was to examine the associations of -866G/A with body fat and the risk of metabolic syndrome in a random sample of 4018 Asians (1858 men and 2160 women) from three ethnic groups (Chinese, Malay, and Indian). The minor allele frequency of -866G/A polymorphism in South Asians was similar to that in whites. After adjustment for covariates including age, cigarette smoking, and physical activity, the -866A/A genotype was associated with higher waist-to-hip ratio as compared with the wild-type genotype in Chinese and Indian men (p = 0.018 and p = 0.046, respectively). Moreover, Indian men with -866A/A genotype had a significantly increased risk of metabolic syndrome as compared with those homozygous for the wild-type (odds ratio, 2.66; 95% confidence interval, 1.21 to 5.88; p = 0.015). Such a risk was mainly caused by the excess presence of hypertriglyceridemia and central obesity. Our findings indicate that the uncoupling protein 2 gene -866G/A polymorphism may increase the risks of central obesity and metabolic syndrome, with greater effects on Asian men.
Dietary fat interacts with the -514C>T polymorphism in the hepatic lipase gene promoter on plasma lipid profiles in a multiethnic Asian population: the 1998 Singapore National Health Survey

Tai ES, Corella D, Deurenberg-Yap M, Cutter J, Chew SK, Tan CE, et al.

J Nutr, 2003 Nov;133(11):3399-408.
PMID: 14608050 DOI: 10.1093/jn/133.11.3399

We have previously reported an interaction between -514C>T polymorphism at the hepatic lipase (HL) gene and dietary fat on high-density lipoprotein-cholesterol (HDL-C) metabolism in a representative sample of white subjects participating in the Framingham Heart Study. Replication of these findings in other populations will provide proof for the relevance and consistency of this marker as a tool for risk assessment and more personalized cardiovascular disease prevention. Therefore, we examined this gene-nutrient interaction in a representative sample of Singaporeans (1324 Chinese, 471 Malays and 375 Asian Indians) whose dietary fat intake was recorded by a validated questionnaire. When no stratification by fat intake was considered, the T allele was associated with higher plasma HDL-C concentrations (P = 0.001), higher triglyceride (TG) concentrations (P = 0.001) and higher HDL-C/TG ratios (P = 0.041). We found a highly significant interaction (P = 0.001) between polymorphism and fat intake in determining TG concentration and the HDL-C/TG ratio (P = 0.001) in the overall sample even after adjustment for potential confounders. Thus, TT subjects showed higher TG concentrations only when fat intake supplied >30% of total energy. This interaction was also found when fat intake was considered as continuous (P = 0.035). Moreover, in the upper tertile of fat intake, TT subjects had 45% more TG than CC individuals (P < 0.01). For HDL-C concentration, the gene-diet interaction was significant (P = 0.015) only in subjects of Indian origin. In conclusion, our results indicate that there are differences in the association of -514C>T polymorphism with plasma lipids according to dietary intake and ethnic background. Specifically, the TT genotype is associated with a more atherogenic lipid profile when subjects consume diets with a fat content > 30%.
APOE polymorphism and lipid profile in three ethnic groups in the Singapore population

Tan CE, Tai ES, Tan CS, Chia KS, Lee J, Chew SK, et al.

Atherosclerosis, 2003 Oct;170(2):253-60.
PMID: 14612205

BACKGROUND: Serum lipid concentrations are modulated by environmental factors such as exercise, alcohol intake, smoking, obesity and dietary intake and genetic factors. Polymorphisms at the Apolipoprotein E (APOE) locus have consistently shown a significant association with total and LDL-cholesterol (LDL-C). However, their impact on HDL-cholesterol (HDL-C) may be population dependent. Having three major ethnic groups within a similar social environment allows us to study the role of genetics and their interactions with lifestyle factors on the serum lipid profile and coronary risk in Asians.
METHODS: This study included 1740 males (1146 Chinese, 327 Malays and 267 Asian Indians) and 1950 females (1329 Chinese, 360 Malays and 261 Asian Indians) with complete data on anthropometric indices, fasting lipids, smoking status, alcohol consumption, exercise frequency and genotype at the APOE locus.
RESULTS: Malays and Asian Indians were more obese compared with the Chinese. Smoking was uncommon in all females but Malay males had significantly higher prevalence of smokers. Malays had the highest LDL-C whilst Indians had the lowest HDL-C, The epsilon 3 allele was the most frequent allele in all three ethnic groups. Malays had the highest frequency of epsilon 4 (0.180 and 0.152) compared with Chinese (0.085 and 0.087) and Indians (0.108 and 0.075) in males and females, respectively. The epsilon 2 allele was the least common in Asian Indians. Total cholesterol (TC) and LDL-C was highest in epsilon 4 carriers and lowest in epsilon 2 carriers. The reverse was seen in HDL-C with the highest levels seen in epsilon 2 subjects. The association between ethnic group and HDL-C differed according to APOE genotype and gender. Asian Indians had the lowest HDL-C for each APOE genotype except in Asian Indian males with epsilon 2, where HDL-C concentrations were intermediate between Chinese and Malays.
CONCLUSION: Ethnic differences in lipid profile could be explained in part by the higher prevalence of epsilon 4 in the Malays. Ethnicity may influence the association between APOE genotypes and HDL-C. APOE genotype showed no correlation with HDL-C in Malay males whereas the association in Asian Indians was particularly marked. Further studies of interactions between genes and environmental factors will contribute to the understanding of differences of coronary risk amongst ethnic groups.
Intragenic linkage disequilibrium structure of the human perilipin gene (PLIN) and haplotype association with increased obesity risk in a multiethnic Asian population

Qi L, Tai ES, Tan CE, Shen H, Chew SK, Greenberg AS, et al.

J Mol Med (Berl), 2005 Jun;83(6):448-56.
PMID: 15770500

Perilipin is a lipid droplet surface protein present in adipocytes and steroidogenic cells. We examined five common single nucleotide polymorphisms (SNPs) at the perilipin (PLIN) locus (PLIN 6209C>T, 10171A>T, 11482G>A, 13041A>G, and 14995A>T) to investigate their association with obesity risk. The study population included 4,131 subjects of three ethnic groups (Chinese, Malay, and Indian) from Singapore. The prevalence of obesity in Malays and Indians was much higher than in Chinese. Moreover, in these groups the prevalence of obesity was three times higher in women than in men. Crude analysis indicated that haplotype 11212 (CAAAT) is shared by Malays and Indians and is significantly associated with increased obesity risk as compared to the most common haplotype 21111 (TAGAA): OR 1.65 (95% CI 1.11-2.46) in Malays and 1.94 (95% CI 1.06-3.53) in Indians. No associations between PLIN haplotypes and obesity risk were found in Chinese. To simplify the haplotype analyses we used a subgroup of three SNPs (11482G>A, 13041A>G, and 14995A>T) in positive linkage disequilibrium. These analyses revealed similar associations, showing that haplotypes XX212 (XXAAT) and XX222 (XXAGT) are associated with increased obesity risk in Malays OR 2.04 (95% CI 1.28-3.25) and 2.05 (95% CI 1.35-3.12) respectively, and that haplotype XXX212 (XXAAT) is significantly associated with increased obesity risk in Indians OR 2.16 (95% CI 1.10-4.26) after adjusting for covariates including age, sex, smoking, alcohol consumption, exercise, and diabetes status. Moreover, individual SNP analyses demonstrated that the PLIN 14995A>T SNP is the most informative single genetic marker for the observed haplotype association, being significantly associated with increased obesity risk in both Malays OR 2.28 (95% CI 1.45-3.57) and Indians OR 2.04 (95% CI 1.08-3.64). These results support the role of the PLIN locus as an ethnically dependent modulator of obesity risk in humans.
Fulltext Polymorphisms at newly identified lipid-associated loci are associated with blood lipids and cardiovascular disease in an Asian Malay population

Tai ES, Sim XL, Ong TH, Wong TY, Saw SM, Aung T, et al.

J Lipid Res, 2009 Mar;50(3):514-520.
PMID: 18987386 DOI: 10.1194/jlr.M800456-JLR200

We conducted a cross-sectional study of Malay participants aged 40-80 years (n = 2,932) to examine the associations between polymorphisms at newly identified, lipid-associated loci with blood lipid levels and prevalent cardiovascular disease (CVD) in a Malay population in Asia. A polymorphism adjacent to the TRIB1 locus (rs17321515) was associated with elevated total cholesterol and LDL-cholesterol (LDL-C) after adjustment for age and sex (both P values <0.007) and with increased risk of coronary heart disease and CVD [odds ratio (OR) 1.23, 95% confidence interval (95% CI) 1.03-1.46; and OR 1.2, 95% CI 1.02-1.42, respectively] under an additive model of inheritance. In addition, using recessive models of inheritance, polymorphisms on chromosome 19 adjacent to the CILP2 and PBX4 loci (rs16996148) and on chromosome 1 at the GALNT2 locus (rs4846914) were associated with elevated HDL-C (P = 0.005) and lower LDL-C (P = 0.048), respectively. Although novel, the former is consistent with the association between this polymorphism and lower blood triglycerides observed in the initial studies conducted in populations of European ancestry. Neither showed statistically significant association with CVD. These observations should form the basis of further investigation to identify the causative polymorphisms at this locus, and also to understand the mechanistic roles that this protein may play in lipoprotein metabolism in Asians and other populations.