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- Jacobsson, Josefin, et al.
(författare)
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Genetic variants near the MGAT1 gene are associated with body weight, BMI and fatty acid metabolism among adults and children
- 2012
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 36:1, s. 119-129
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Recently a genome-wide association analysis from five European populations identified a polymorphism located downstream of the mannosyl-(α-1,3)-glycoprotein-β-1,2-N-acetylglucosaminyltransferase (MGAT1) gene that was associated with body-weight. In the present study, associations between MGAT1 variants combined with obesity and insulin measurements were investigated in three cohorts. Levels of fatty acids and estimated measures of Δ desaturases were also investigated among adult men. Design: Six polymorphisms downstream of MGAT1 were genotyped in a cross-sectional cohort of 1152 Swedish men. Three polymorphisms were further analyzed in a case-control study of 1076 Swedish children and in a cross-sectional study of 2249 Greek children. Results: Three polymorphisms, rs12186500 (odds ratio (OR): 1.892, 95% confidence interval (CI): 1.237-2.895, P=0.003), rs1021001 (OR: 2.102, 95% CI: 1.280-3.455, P=0.003) and rs4285184 (OR: 1.587, 95% CI: 1.024-2.459, P=0.038) were associated with a higher prevalence of obesity among the adult men and a trend for obesity was observed for rs4285184 among the Swedish (OR: 1.205, 95% CI: 0.987-1.471, P=0.067) and Greek children (OR: 1.192, 95%CI: 0.978-1.454, P=0.081). Association with body weight was observed for rs12186500 (P=0.017) and rs4285184 (P=0.024) among the men. The rs1021001 and rs4285184 were also associated with body mass index (BMI) in the two Swedish cohorts and similar trends were observed among the Greek children. The combined effect size for rs1021001 and rs4285184 on BMI z-score from a meta-analysis was 0.233 (95% CI:0.093-0.373, P=0.001) and 0.147 (95% CI:0.057-0.236, P=0.001), respectively. We further observed associations between the genetic variants and fatty acids (P<0.039) and estimated measures of Δ desaturases (P<0.040), as well as interactions for rs12186500 (P<0.019) with an effect on BMI. No association was found with homeostatic model assessment-insulin resistance in any cohort but increased insulin levels, insulin response and decreased insulin sensitivity were observed among the children (P<0.038). Conclusion: Genetic variants downstream MGAT1 seem to influence susceptibility to obesity. Moreover, these genetic variants affect the levels of serum unsaturated fatty acids and Δ desaturase indices, variables previously shown to correlate with obesity.
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| 2. |
- Jacobsson, Josefin A., et al.
(författare)
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Major gender difference in association of FTO gene variant among severely obese children with obesity and obesity related phenotypes.
- 2008
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 368:3, s. 476-482
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have shown that SNPs in the FTO gene predispose to childhood and adult obesity. In this study, we examined the association between variants in FTO and KIAA1005, a gene that maps closely to FTO, and obesity, as well as obesity related traits among 450 well characterised severely obese children and 512 normal weight controls. FTO showed significant association with several obesity related traits while SNPs in KIAA1005 did not. When stratified by gender, the FTO variant rs9939609 showed association with obesity and BMI among girls (P=0.006 and 0.004, respectively) but not among boys. Gender differences were also found in the associations of the FTO rs9939609 with obesity related traits such as insulin sensitivity and plasma glucose. This study suggests that FTO may have an important role for gender specific development of severe obesity and insulin resistance in children.
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| 3. |
- Jacobsson, J. A., et al.
(författare)
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Novel genetic variant in FTO influences insulin levels and insulin resistance in severely obese children and adolescents.
- 2008
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 32:11, s. 1730-1735
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND The global prevalence of obesity and overweight is increasing rapidly among adults as well as among children and adolescents. Recent genome-wide association studies have provided strong support for association between variants in the FTO gene and obesity. We sequenced regions of the FTO gene to identify novel variants that are associated with obesity and related metabolic traits. RESULTS We screened exons 3 and 4 including exon-intron boundaries in FTO in 48 obese children and adolescents and identified three novel single nucleotide polymorphism in the fourth intronic region, (c.896+37A>G, c.896+117C>G and c.896+223A>G). We further genotyped c.896+223A>G in 962 subjects, 450 well-characterized obese children and adolescents and 512 adolescents with normal weight. Evidence for differences in genotype frequencies were not detected for the c.896+223A>G variant between extremely obese children and adolescents and normal weight adolescents (P=0.406, OR=1.154 (0.768-1.736)). Obese subjects with the GG genotype, however, had 30% increased fasting serum insulin levels (P=0.017) and increased degree of insulin resistance (P=0.025). There were in addition no differences in body mass index (BMI) or BMI standard deviation score (SDS) levels among the obese subjects according to genotype and the associations with insulin levels and insulin resistance remained significant when adjusting for BMI SDS. CONCLUSION These findings suggest that this novel variant in FTO is affecting metabolic phenotypes such as insulin resistance, which are not mediated through differences in BMI levels.
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| 4. |
- Rask-Andersen, Mathias, et al.
(författare)
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Determination of obesity associated gene variants related to TMEM18 through ultra-deep targeted re-sequencing in a case-control cohort for pediatric obesity.
- 2015
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Ingår i: Genetical Research. - 0016-6723 .- 1469-5073. ; 97
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have revealed association of a locus approximately 25b downstream of the TMEM18 gene with body mass and obesity. We utilized targeted re-sequencing of the body mass associated locus in proximity of TMEM18 in a case-control population of severely obese children and adolescents from the Stockholm area. We expanded our study to include the TMEM18 gene itself, with the aim of identifying body mass associated genetic variants. Sequencing was performed on the SOLiD platform, on long-range PCR fragments generated through targeted amplification of the regions of interest. Candidate single nucleotide polymorphisms (SNPs) were validated by TaqMan genotyping. We were able to observe 131 SNPs across the re-sequenced regions. Chi squared tests comparing the allele frequencies between cases and controls revealed 57 SNPs as candidates for association with obesity. Validation and replication genotyping revealed robust associations for SNPs within the haplotype block region located downstream from the TMEM18 gene. This study provides a high resolution map of the genetic variation pattern in the TMEM18 gene, as well as the associated haplotype block, and further strengthens the association of variants within the proximal haplotype block with obesity and body mass.
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| 6. |
- Sällman Almén, Markus, et al.
(författare)
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Determination of the obesity-associated gene variants within the entire FTO gene by ultra-deep targeted sequencing in obese and lean children.
- 2013
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 37:3, s. 424-431
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Tidskriftsartikel (refereegranskat)abstract
- Background:The Fat mass and obesity-associated gene (FTO) was the first gene reliably associated with body mass index in genome-wide association studies on a population level. At present, the genetic variations within the FTO gene are still the common variants that have the largest influence on body mass index.Methods:In the current study, we amplified the entire FTO gene, in total 412 Kbp, in over 200 long-range PCR fragments from each individual, from 524 severely obese and 527 lean Swedish children, and sequenced the products as two DNA pools using massive parallel sequencing (SOLiD).Results:The sequencing achieved very high coverage (median 18 000 reads) and we detected and estimated allele frequencies for 705 single nucleotide polymorphisms (SNPs) (19 novel) and 40 indels (24 novel) using a sophisticated statistical approach to remove false-positive SNPs. We identified 19 obesity-associated SNPs within intron one of the FTO gene, and validated our findings with genotyping. Ten of the validated obesity-associated SNPs have a stronger obesity association (P<0.007) than the commonly studied rs9939609 SNP (P<0.012).Conclusions:This study provides a comprehensive obesity-associated variation map of FTO, identifies novel lead SNPs and evaluates putative causative variants. We conclude that intron one is the only region within the FTO gene associated with obesity, and finally, we establish next generation sequencing of pooled DNA as a powerful method to investigate genetic association with complex diseases and traits.
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