Contribution of several candidate gene polymorphisms in the determination of adiposity changes: results from the Québec Family Study

Neuropeptide Neuromedin B does not alter body weight and glucose homeostasis nor does it act as an insulin-releasing peptide

Neuromedin B (NMB) is a member of the neuromedin family of neuropeptides with a high level of region-specific expression in the brain. Several GWAS studies on non-obese and obese patients suggested that polymorphisms in NMB predispose to obesity by affecting appetite control and feeding preference. Furthermore, several studies proposed that NMB can act as an insulin releasing peptide. Since the functional study has never been done, the in vivo role of NMB as modulator of weight gain or glucose metabolism remains unclear. Here, we generated Nmb conditional mice and nervous system deficient NmB mice. We then performed olfactory and food preference analysis, as well as metabolic analysis under standard and high fat diet. Additionally, in direct islet studies we evaluated the role of NMB on basal and glucose-stimulated insulin secretion in mouse and humans.

The Single Nucleotide Polymorphism PPARG2 Pro12Ala Affects Body Mass Index, Fat Mass, and Blood Pressure in Severely Obese Patients

BACKGROUND

The PPARG2 Pro12Ala (rs1801282) and IL6 -174G >C (rs1800795) have important function in body weight regulation and a potential role in obesity risk. We aimed to investigate the association between PPARG2 Pro12Ala and IL6 -174G >C variants and the genotypes interaction with body composition, metabolic markers, food consumption, and physical activity in severely obese patients.

METHODS

150 severely obese patients (body mass index (BMI) ≥ 35 kg/m²) from Central Brazil were recruited. Body composition, metabolic parameters, physical activity, and dietary intake were measured. The genotype was determined by the qPCR TaqMan Assays System. Multiple linear regression and multiple logistic regression models were fitted adjusting for confounders.

RESULTS

Ala carriers of the Pro12Ala polymorphism had higher adiposity measures (BMI: p=0.031, and fat mass: p=0.049) and systolic blood pressure (p=0.026) compared to Pro homozygotes. We found no important associations between the -174G >C polymorphism and obesity phenotypes. When genotypes were combined, individuals with genotypes ProAla + AlaAla and GC + CC presented higher BMI (p=0.029) and higher polyunsaturated fatty acids (PUFAs) consumption (p=0.045) compared to the ones with genotypes ProPro and GG, and individuals carriers of the PPARG2 Ala allele only (genotype ProAla + AlaAla and GG) had higher fat mass and systolic and diastolic blood pressure compared to the ones with genotypes ProPro and GG.

CONCLUSIONS

Severely obese individuals carrying the Ala allele of the PPARG2 Pro12Ala polymorphism had higher measures of adiposity and blood pressure, while no important associations were found for the IL6 -174G >C polymorphism.

Angiotensin-converting enzyme gene insertion/deletion polymorphism in nutritional disorders in children

PURPOSE

The aim of this study was to establish the role of angiotensin-converting enzyme gene insertion/deletion (ACE I/D) polymorphism in determining obesity or undernutrition in a child population in Romania.

METHODS

We assessed 293 consecutively hospitalized patients in a tertiary emergency pediatric hospital. The patients were divided, according to body mass index (BMI), into three groups: group I, the control group consisting of 126 children, group II patients with undernutrition (85 patients) and group III patients with obesity (82 patients). ACE I/D polymorphisms were performed in all three patient groups, as well as the measuring of anthropometric parameters [middle upper arm circumference (MUAC), tricipital skinfold thickness (TST)]. All patients also underwent paraclinical evaluations (protein and albumin). The cutoffs criteria for moderate undernutrition were: BMI between -2.0 SD and -3.0 SD, severe undernutrition: BMI <-3.0 SD, moderate obesity: BMI between +2.0 SD and +3.0 SD and severe obesity: BMI >+3.0 SD.

RESULTS

We observed that DD genotype (64.7%) was prevalent in the moderate undernutrition group, while ID (35.3%) and II genotypes were higher in the subgroup of severe undernutrition, with significant correlations in DD and ID genotype groups between BMI and MUAC, protein and albumin (p < 0.0001). In the obese group, we observed significant correlations in DD genotype, between BMI and MUAC (p = 0.0014) and TST, and for II genotype, between BMI and TST (p = 0.0071). II genotype was associated with severe obesity, while D allele carriers were associated with moderate undernutrition and moderate obesity.

CONCLUSION

BMI, MUAC, TST and serum protein levels are correlated with D allele carriers of ACE genes in children with moderate undernutrition and moderate obesity, whereas II genotype is an unfavorable prognostic factor corresponding to severe obesity and severe undernutrition.

Role of leptin G-2548A polymorphism in age- and gender-specific development of obesity

Leptin is involved in the regulation of food intake and energy expenditure, and therefore, is central to adipositysensing pathway. We examined the relationship of the leptin G-2548A polymorphism with obesity and obesityrelated anthropometric and metabolic parameters in a total of 394 (239 obese and 155 non-obese) subjects between 5 and 45 years of age. Body weight, height, waist circumference (WC), hip circumference (HC) and blood pressure (BP) were measured. Body mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Levels of fasting blood glucose (FBG), insulin, leptin and leptin receptor were determined, and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The LEP G-2548A polymorphism showed association with obesity in children and adolescents (less than or equal to 18 years of age) but not in adults. However, analysis by gender stratification revealed association with obesity in girls only. In addition, G-2548A polymorphism showed association with BMI, WC, HC, fasting blood glucose and serum leptin levels. This suggests that G-2548A polymorphism may influence the susceptibility to metabolic disturbances and obesity at an early life. Further investigation with a larger sample size is required to validate the effect of LEP G-2548A polymorphism in obese Pakistani girls.

Synergistic effect of LEP and LEPR gene polymorphism on body mass index in a Chinese population

Both leptin (LEP) and leptin receptor (LEPR) are important in the regulation of body weight. In this study, we evaluated the individual and combined effects of a polymorphic microsatellite marker in the LEP gene 3' flanking region and two polymorphisms (Lys109Arg and Lys656Asn) of the LEPR gene on metabolic markers for obesity in a Chinese population. The genotypes of polymorphisms in LEP and LEPR gene were determined by PCR and SSCP assay in 230 simple obese subjects and 202 control subjects of Chinese population. Logistic regression analysis showed that polymorphism in LEP gene 3' flanking region was associated with waist/hip ratio (WHR) (P = 0.042). Individually, Lys109Arg variant in LEPR gene was associated with systolic blood pressure (P = 0.031) in males, and Lys656Asn variant was associated with serum triglyceride level (P = 0.026). Interestingly, only subjects that simultaneously exhibit all three polymorphisms showed a significantly elevated BMI (29.30 ± 0.85 vs 26.91 ± 1.19, P = 0.037). Taken together, our data suggest that a combination of polymorphism in the LEP gene 3' flanking region, and Lys109Arg, Lys656Asn variants in LEPR gene is associated with obesity in Chinese Han population.

Leptin and leptin receptor gene polymorphisms and their association with plasma leptin levels and obesity in a multi-ethnic Malaysian suburban population

Background

This study was to investigate the prevalence of single nucleotide polymorphisms (SNPs) in leptin gene LEP (A19G and G2548A) and leptin receptor gene LEPR (K109R and Q223R) and their association with fasting plasma leptin level (PLL) and obesity in a Malaysian suburban population in Kampar, Perak.

Methods

Convenience sampling was performed with informed consents, and the study sample was drawn from patients who were patrons of the Kampar Health Clinic. A total of 408 subjects (mean age, 52.4 ± 13.7 years; 169 men, 239 women; 190 obese, 218 non-obese; 148 Malays, 177 ethnic Chinese, 83 ethnic Indians) participated. Socio-demographic data and anthropometric measurements were taken, and genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

Results

The LEP A19G, G2548A and LEPR K109R, Q223R variant allele frequencies were 0.74, 0.67 and 0.61, 0.79, respectively. The genotype and allele distributions of these gene variants were significantly different among ethnic groups, but not among body mass index (BMI) classes. Subjects with LEPR K109 and Q223 allele had significantly higher systolic blood pressure and adiposity indices after adjustment for ethnicity (higher BMI, total body and subcutaneous fat; lower skeletal muscle percentage). Subjects with LEPR 109R allele had lower PLL than their wild-type allele counterparts. The influence of LEP A19G and G2548A SNPs on blood pressures, anthropometrics, and PLL was not evident. Interestingly, synergistic effect of the LEP and LEPR SNPs was observed as subjects homozygous for all four SNPs studied exhibited significantly higher subcutaneous fat and PLL than those with other genotype combinations.

Conclusions

The LEP and LEPR SNPs in this study may not be an obesity marker among Malaysians in this population, but were associated with ethnicity. Our findings suggest that each of these SNPs contributes to minor but significant variation in obesity-related traits and in combination they display synergistic effects on subcutaneous fat and PLL.

Relationship between variants of the leptin gene and obesity and metabolic biomarkers in Brazilian individuals

OBJECTIVE

The relationship between variants of the leptin gene (LEP) and obesity and metabolic biomarkers was investigated in Brazilian individuals.

SUBJECTS AND METHODS

One-hundred-ten obese (BMI > 30 kg/m(2)) and 100 non-obese individuals (145 women and 65 men, aged 49 +/- 14 years) were randomly selected. Plasma leptin, glycemia, serum lipid measurements and LEP -2548G>A and 3'HVR polymorphisms were analyzed.

RESULTS

The LEP -2548GG genotype was associated with a 2.2% and 2.0% increase in BMI (p = 0.009) and plasma leptin (p = 0.031), respectively. 3'HVR I/II (classes I/I+I/II) genotypes contributed with 1.8% of BMI values (p = 0.046). LEP I/G combined genotypes (I/IGG, I/IGA and I/IIGG) were associated with obesity, and increased BMI, waist circumference, leptin and triglycerides (p < 0.05). These relationships were found in women (p < 0.05) but not in men. LEP I/G combined genotypes were not associated with hypertension, hyperglycemia, dyslipidemia and coronary artery disease.

CONCLUSIONS

LEP I/G combined genotypes are associated with obesity-related metabolic biomarkers and phenotype in a gender-dependent manner.

Apolipoprotein A5 and lipoprotein lipase interact to modulate anthropometric measures in Hispanics of Caribbean origin

Apolipoprotein A5 (APOA5) and lipoprotein lipase (LPL) proteins interact functionally to regulate lipid metabolism, and single-nucleotide polymorphisms (SNPs) for each gene have also been associated independently with obesity risk. Evaluating gene combinations may be more effective than single SNP analyses in identifying genetic risk, but insufficient minor allele frequency (MAF) often limits evaluations of potential epistatic relationships. Populations with multiple ancestral admixtures may provide unique opportunities for evaluating genetic interactions. We examined relationships between LPL m107 (rs1800590) and APOA5 S19W (rs3135506) and lipid and anthropometric measures in Caribbean origin Hispanics (n = 1,019, aged 45-75 years) living in the Boston metropolitan area. Significant interaction terms between LPL m107 and APOA5 S19W were observed for BMI (P = 0.003) and waist circumference (P = 0.019). Higher BMI (P = 0.001), waist (P = 0.011) and hip (P = 0.026) circumference were observed in minor allele (G) carriers for LPL m107 who also carried the APOA5 S19W minor allele (G). Additionally, extreme obesity (BMI > or = 40 kg/m(2)) risk was higher (odds ratio = 4.02; 95% confidence interval: 1.81-8.91; global P = 0.008) for minor allele carriers for both SNPs (LPL TG+GG, APOA5 CG+GG) compared to major allele carriers for both SNPs. In summary, we identified significant interactions for APOA5 S19W and LPL m107 for obesity in Caribbean Hispanics. Population-specific MAFs increase the difficulties of replicating gene-gene interactions, but may support the hypothesis that combinations of frequencies in selected genes could heighten obesity susceptibility in a given population. Analyses of gene-gene interactions may improve understanding of genetically based obesity risk, and underscore the need for further study of groups with multiple ancestral admixtures.

PPARG genotype accounts for part of individual variation in body weight reduction in response to calorie restriction

Several studies indicate that expression of the peroxisome proliferator-activated receptor gamma (PPARG) gene is influenced by calorie restriction. The aim of this study was to investigate whether PPARG gene variations are associated with weight reduction and changes in coronary heart disease (CHD) risk factors in response to a 14-week calorie restriction. In total, 95 middle-aged, Japanese women (BMI>or=25 kg/m2) enrolled as subjects for 14 weeks and attended weekly dietary lectures instructing them on how to consume a nutritionally balanced diet of 1,200 kcal/day. Eight single-nucleotide polymorphisms (SNPs) in the PPARG gene (rs1801282 (Pro/Ala), rs2292101, rs2959272, rs1386835, rs709158, rs1175540, rs1175544, and rs1797912) were analyzed. Body weight decreased significantly (-7.7+/-3.1 kg; -11.3+/-4.4%) during the intervention. Six PPARG SNPs (rs2959272, rs1386835, rs709158, rs1175540, rs1175544, and rs1797912) were significantly associated with the weight reduction, with rs1175544 having the strongest association (P=0.004). No differences across the rs1175544 genotypes were observed in any of the blood analyses or in blood pressure. In a multiple regression analysis, the rs1175544 genotypes accounted for 7% of the total weight reduction variance. These data suggest that one SNP of the PPARG genotype accounted for a significant portion of the total body weight reduction variance in response to a short-term intervention consisting of calorie restriction; however, no relationship was found between these SNPs and the changes in CHD risk factors which accompanied weight loss.

Effect of ID ACE gene polymorphism on dietary composition and obesity-related anthropometric parameters in the Czech adult population

The aim of this study was to investigate the possible associations between insertion/deletion (ID) polymorphism in angiotensin-converting enzyme (ACE) (dbSNP rs 4646994) with the food intake and body composition in the Czech non-obese, obese and extremely obese populations. A total of 453 various-weighted individuals were enrolled in the study and were according to their BMI assigned into following subgroups, such as obese (30 </= BMI < 40), morbidly obese (BMI >/=40) and non-obese (20 < BMI < 30) subjects. Both the obese cases and the non-obese controls underwent the identical subset of standardized examinations (BMI, % body fat, waist-to-hip ratio, skin fold thickness, native dietary composition examined by 7-day food records, etc.). No significant case-control differences in genotype distributions or allelic frequencies were observed. There were no differences in genotype frequencies between males and females either. The prevalence of obesity was significantly higher among subjects with the II genotype (42 %) when compared with those with DD (36%) and those with ID (37%) genotypes (P = 0.04). When compared with carbohydrate intake in the whole studied cohort, the odds ratios of carrying the DD allele in the morbidly obese cohort were 0.84 (95% CI 0.34, 2.10, P = 0.17), 0.27 (0.07, 0.98, P = 0.02), and 4.25 (1.44, 12.51, P = 0.005) in those individuals consuming <210, 210-260, and >260 g of carbohydrates/day, respectively. Based on our findings, the ID ACE polymorphism could represent a gene modulator of carbohydrate intake in morbidly obese Czech population; the strong significant effect of DD genotype was observed in the phenotypes of extreme obesity with the highest carbohydrate intake.

Genome-wide association study of anthropometric traits in Korcula Island, Croatia

AIM

To identify genetic variants underlying six anthropometric traits: body height, body weight, body mass index, brachial circumference, waist circumference, and hip circumference, using a genome-wide association study.

METHODS

The study was carried out in the isolated population of the island of Korcula, Croatia, with 898 adult examinees who participated in the larger DNA-based genetic epidemiological study in 2007. Anthropometric measurements followed standard internationally accepted procedures. Examinees were genotyped using HumanHap 370CNV chip by Illumina, with a genome-wide scan containing 316730 single nucleotide polymorphisms (SNP).

RESULTS

A total of 11 SNPs were associated with the investigated traits at the level of P<10(-5), with one SNP (rs7792939 in gene zinc finger protein 498, ZNF498) associated with body weight, hip circumference, and brachial circumference (P=3.59-5.73 x 10(-6)), and another one (rs157350 in gene delta-sarcoglycan, SGCD) with both brachial and hip circumference (P=3.70-6.08 x 10(-6). Variants in CRIM1, a gene regulating delivery of bone morphogenetic proteins to the cell surface, and ITGA1, involved in the regulation of mesenchymal stem cell proliferation and cartilage production, were also associated with brachial circumference (P=7.82 and 9.68 x 10(-6), respectively) and represent interesting functional candidates. Other associations involved those between genes SEZ6L2 and MAX and waist circumference, XTP6 and brachial circumference, and AMPA1/GRIA1 and height.

CONCLUSION

Although the study was underpowered for the reported associations to reach formal threshold of genome-wide significance under the assumption of independent multiple testing, the consistency of association between the 2 variants and a set of anthropometric traits makes CRIM1 and ITGA1 highly interesting for further replication and functional follow-up. Increased linkage disequilibrium between the used markers in an isolated population makes the formal significance threshold overly stringent, and changed allele frequencies in isolate population may contribute to identifying variants that would not be easily identified in large outbred populations.

Relation between adiponectin 45 T/G polymorphism and dietary composition in the Czech population

In this study on 138 Czech Caucasians, the ADIPOQ 45T/G polymorphism was associated with the dietary composition. As the GG homozygotes were associated with the increased intake of carbohydrates, we suggest that a proportion of the prodiabetogenic effect of the polymorphism might be due to its influence on eating behaviour.

Obesity genes: so close and yet so far

Little is known about genetic variants that predispose individuals toward leanness or fatness. This minireview highlights recent advances in the study of human populations, animal models and synergistic efforts as described by De Luca and colleagues in BMC Genetics, which are beginning to harvest low-hanging fruit in the search for obesity genes.

Risk factors for overweight and obesity, and changes in body mass index of Chinese adults in Shanghai

Background

Over the past two decades, the prevalence of overweight or obesity has increased in China. The aims of this study were to firstly assess the baseline prevelences and the risk factors for overweight and obesity, and secondly to detect the changes of body mass index (BMI) over a follow-up period in Chinese adults in Shanghai.

Methods

The data set of a population-based longitudinal study was analyzed. Anthropometric and biochemical data were collected for 5364 subjects (aged 25–95 years) during a period of 1998–2001. Among those individuals, 3032 subjects were interviewed and reexamined at the second survey from 2003 to 2004. Then the standardized prevalences for overweight and obesity were calculated using baseline data; the possible contributing factors of overweight and obesity were detected using binary logistic regression analysis; and the changes of BMI were evaluated after an average of 3.6-year follow-up period.

Results

(1) According to the WHO standard and the Chinese standard, the sex- and age-standardized prevalences were 27.5% and 32.4% for overweight, and 3.7% and 9.1% for obesity, respectively. (2) The risks of overweight and obesity differed among different age groups. Family history of obesity increased the risk of overweight and obesity by about 1.2-fold for both genders. Current male smokers had a lower risk of overweight and obesity (OR = 0.76, p < 0.05) than nonsmokers. In contrast, current male drinkers had a higher risk of overweight and obesity (OR = 1.42, p < 0.05) than nondrinkers. Compared with low-educated women, medium- and high- educated women were at lower risk of overweight and obesity, and the corresponding ORs (95% CIs) were 0.64 (0.52–0.79) and 0.50(0.36–0.68), respectively. (3) The annual changes of BMI means ranged from an increase of 0.1 kg/m² to a decrease of 0.2 kg/m² (by genders and age groups). Meanwhile, the BMI increase was statistically significant in the 35–44 years age group, and the BMI decrease was significant above 65 years for both genders.

Conclusion

This study showed high prevalence of overweight and obesity in Shanghai metropolis populations. The risk factors of overweight and obesity were multifactorial and gender specific. After 3.6 years, BMI means changed slightly, BMI increased mainly in middle-aged individuals and decreased in old individuals.