Dataset Information

Brain-derived neurotrophic factor gene variants and obesity in former smokers.

ABSTRACT:

Objective

From genome-wide association studies, brain-derived neurotrophic factor (BDNF) locus on chromosome 11 was the only SNP associated with both smoking and body mass index (BMI) in European, African and Asian population. This study aims to explore the unique genetic predisposition to obesity in former smokers by examining the effects of BDNF on BMI and waist circumference (WC).

Methods

The study design is case-control study with a cohort validation in supplementary. We included 15,072 ethnic Chinese participants in the Guangzhou Biobank Cohort Study (GBCS) with data of four BDNF SNPs related to both BMI and smoking behavior. We used baseline smoke exposure data in 2003-2007 and follow-up outcomes of general obesity (by BMI) and central obesity (WC) in 2008-2012. Odds ratios (ORs) and 95% confidence intervals (CIs) for general obesity and central obesity associated with these SNPs were derived from logistic regression.

Results

Of 15,072 participants (3169 men and 11,903 women), 1664 (11.0%) had general and 7868 (52.2%) had central obesity. In 1233 former smokers, the rs6265 GG, versus AA, genotype was associated with higher risks of general obesity (OR = 1.79, 95% CI = 1.06-3.01) and central obesity (OR = 2.08, 95% CI = 1.47-2.92) after adjustment. These associations were not significant in never or current smokers. In former heavy (≥20 cigarettes/day) smokers, the rs6265 GG genotype showed a higher odds for general obesity (OR = 2.15, 95% CI = 1.05-4.40), while no association was found in former light (1-9 cigarettes/day) smokers. Similar results were found for the association of rs6265 with central obesity and for the associations of other two BDNF SNPs (rs4923457 and rs11030104) with both general and central obesity.

Conclusions

We firstly identified the genetic predisposition (BDNF SNPs) to general and central obesity in former smokers, particularly in former heavy smokers. The different associations of the SNPs for general/central obesity in different smoke exposure groups may be related to the competitive performance of the sites and epigenetic modification, which needs further study.

SUBMITTER: Yang SS

PROVIDER: S-EPMC8442367 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BackgroundBrain-derived neurotrophic factor (BDNF) has been found to be important in energy homeostasis in animal models, but little is known about its role in energy balance in humans. Heterozygous, variably sized, contiguous gene deletions causing haploinsufficiency of the WT1 and PAX6 genes on chromosome 11p13, approximately 4 Mb centromeric to BDNF (11p14.1), result in the Wilms' tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR) syndrome. Hyperphagia and obesity were observed in a subgroup of patients with the WAGR syndrome. We hypothesized that the subphenotype of obesity in the WAGR syndrome is attributable to deletions that induce haploinsufficiency of BDNF.MethodsWe studied the relationship between genotype and body-mass index (BMI) in 33 patients with the WAGR syndrome who were recruited through the International WAGR Syndrome Association. The extent of each deletion was determined with the use of oligonucleotide comparative genomic hybridization.ResultsDeletions of chromosome 11p in the patients studied ranged from 1.0 to 26.5 Mb; 58% of the patients had heterozygous BDNF deletions. These patients had significantly higher BMI z scores throughout childhood than did patients with intact BDNF (mean [+/-SD] z score at 8 to 10 years of age, 2.08+/-0.45 in patients with heterozygous BDNF deletions vs. 0.88+/-1.28 in patients without BDNF deletions; P=0.03). By 10 years of age, 100% of the patients with heterozygous BDNF deletions (95% confidence interval [CI], 77 to 100) were obese (BMI > or = 95th percentile for age and sex) as compared with 20% of persons without BDNF deletions (95% CI, 3 to 56; P<0.001). The critical region for childhood-onset obesity in the WAGR syndrome was located within 80 kb of exon 1 of BDNF. Serum BDNF concentrations were approximately 50% lower among the patients with heterozygous BDNF deletions (P=0.001).ConclusionsAmong persons with the WAGR syndrome, BDNF haploinsufficiency is associated with lower levels of serum BDNF and with childhood-onset obesity; thus, BDNF may be important for energy homeostasis in humans.

Project description:BACKGROUND In a previous study, we reported that pro-brain-derived neurotrophic factor (proBDNF) was involved in the pathology of alcohol dependence, and the single-nucleotide polymorphism (SNP) Val66Met was located at the prodomain of the brain-derived neurotrophic factor gene (BDNF). This polymorphism has been reported to affect intracellular trafficking and activity-dependent secretion of BDNF. Our present research investigated the relationships between the BDNF Val66Met polymorphism and the plasma levels of proBDNF and mature brain-derived neurotrophic factor (mBDNF) in patients with alcohol dependence. MATERIAL AND METHODS The BDNF gene Val66Met polymorphism was genotyped in 59 alcohol-dependent patients and 37 age- and sex-matched controls, and the plasma levels of proBDNF and mBDNF were assessed by enzyme-linked immunosorbent assay in all participants. RESULTS No association was found between the BDNF gene Val66Met polymorphism and alcohol dependence (P>0.05). In comparison with the control group, the level of plasma proBDNF in the alcohol-dependence group was notably increased (Z=-2.228, P=0.026), while the level of mBDNF was remarkedly decreased (Z=-2.014, P=0.044). In the alcohol-dependence group, significant associations were not found between the Val66Met polymorphisms and proBDNF and mBDNF plasma levels (P>0.05). The plasma level of proBDNF was positively correlated with the average daily alcohol consumption in the last month (r=0.344, P=0.008) and drinking history (r=0.317, P=0.014), while the plasma level of mBDNF had negative effects (r=-0.361, P=0.005, with the average daily alcohol consumption; r=-0.427, P=0.001, with drinking history). CONCLUSIONS The BDNF gene Val66Met polymorphism does not appear to affect the secretion of proBDNF and mBDNF in Chinese patients with alcohol dependence. Furthermore, this study reconfirmed that the plasma levels of proBDNF and mBDNF were correlated with the average daily alcohol consumption in the last month and with drinking history.