OBJECTIVE-Three independent studies have shown that variation in the fat mass and obesity-associated (FTO) gene associates with BMI and obesity. In the present study, the effect of FTO variation on metabolic traits including obesity, type 2 diabetes, and related quantitative phenotypes was examined. RESEARCH DESIGN AND METHODS-The FTO rs9939609 polymorphism was genotyped in a total of 17,508 Danes from five different study groups.RESULTS-In studies of 3,856 type 2 diabetic case subjects and 4,861 normal glucose-tolerant control subjects, the minor A-allele of rs9939609 associated with type 2 diabetes (odds ratio 1.13 [95% CI 1.06 -1.20], P ϭ 9 ϫ 10 Ϫ5 ). This association was abolished when adjusting for BMI (1.06 [0.97-1.16], P ϭ 0.2). Among 17,162 middle-aged Danes, the A-allele associated with overweight (1.19 [1.13-1.24], P ϭ 1 ϫ 10 Ϫ12 ) and obesity (1.27 [1.20 -1.34], P ϭ 2 ϫ 10 Ϫ16 ). Furthermore, obesity-related quantitative traits such as body weight, waist circumference, fat mass, and fasting serum leptin levels were significantly elevated in A-allele carriers. An interaction between the FTO rs9939609 genotype and physical activity (P ϭ 0.007) was found, where physically inactive homozygous risk A-allele carriers had a 1.95 Ϯ 0.3 kg/m 2 increase in BMI compared with homozygous T-allele carriers.CONCLUSIONS-We validate that variation in FTO is associated with type 2 diabetes when not adjusted for BMI and with an overall increase in body fat mass. Furthermore, low physical activity seems to accentuate the effect of FTO rs9939609 on body fat accumulation. Diabetes 57:95-101, 2008 W orldwide incidence of obesity has increased dramatically and is today one of the leading causes of lifestyle-related disorders such as type 2 diabetes and premature cardiovascular disease. Association between common forms of obesity and genes such as GAD2 (1), ENPP1 (2), and INSIG2 (3) have been reported but difficult to validate (4 -6). Recently, variation in the fat mass and obesity-associated (FTO) gene was reported to associate with type 2 diabetes and increased fat mass. As a part of the Wellcome Trust Case Control Consortium genome-wide association study, which included 1,924 U.K. type 2 diabetic patients and 2,938 U.K. normoglycemic control subjects, an FTO variant (rs9939609) was found to associate with type 2 diabetes; however, this association abolished following adjustment for BMI (7). Subsequently, an association with overweight and obesity was demonstrated in seven population-based study samples comprising a total of 19,424 white European adults and two birth cohorts including 10,172 white European children. Moreover, evidence was presented that the increase in BMI resulted from an overall increase in body fat, evaluated by waist circumference and fat mass estimates, including skinfold measures (7).In another independent study, the effect of 48 neutral single-nucleotide polymorphisms (SNPs) on obesity was tested in 2,900 obese and 5,100 control subjects of European ancestry, and the FTO rs1121980 polymorphism, also ...

BackgroundThe INSIG2 rs7566605 and PFKP rs6602024 polymorphisms have been identified as obesity gene variants in genome-wide association (GWA) studies. However, replication has been contradictory for both variants. The aims of this study were to validate these obesity-associations through case-control studies and analyses of obesity-related quantitative traits. Moreover, since environmental and genetic factors may modulate the impact of a genetic variant, we wanted to perform such interaction analyses. We focused on physical activity as an environmental risk factor, and on the GWA identified obesity variants in FTO (rs9939609) and near MC4R (rs17782313) as genetic risk factors.Materials and MethodsThe four variants were genotyped in a combined study sample comprising a total of 18,014 subject ascertained from, the population-based Inter99 cohort (n = 6,514), the ADDITION screening cohort (n = 8,662), a population-based study sample (n = 680) and a type 2 diabetic patient group (n = 2,158) from Steno Diabetes Center.ResultsNo association with overweight, obesity or obesity-related measures was shown for either the INSIG2 rs7566605 or the PFKP rs6602024 variants. However, an interaction between the INSIG2 rs7566605 variant and the level of self-reported physical activity (p Int = 0.004) was observed. A BMI difference of 0.53 (SE 0.42) kg/m2 was found when comparing physically passive homozygous C-allele carriers with physically passive G-allele carriers. No interactions between the two variants and FTO rs9939609 and MC4R rs17782313 were observed.ConclusionsThe INSIG2 rs7566605 and PFKP rs6602024 polymorphisms play no apparent role in the development of common forms of obesity in the Danish population. However, if replicated, the INSIG2 rs7566605 may influence the level of BMI in combination with the level of physical activity.

Intervertebral disc calcification and herniation commonly affects Dachshund where the predisposition is caused by an early onset degenerative process resulting in disc calcification. A continuous spectrum of disc degeneration is seen within and among dog breeds, suggesting a multifactorial etiology. The number of calcified discs at 2 years of age determined by a radiographic evaluation is a good indicator of the severity of disc degeneration and thus serves as a measure for the risk of developing intervertebral disc herniation. The aim of the study was to identify genetic variants associated with intervertebral disc calcification in Dachshund through a genome-wide association (GWA) study. Based on thorough radiographic examinations, 48 cases with ≥ 6 disc calcifications or surgically treated for disc herniation and 46 controls with 0-1 disc calcifications were identified. GWA using the Illumina CanineHD BeadChip identified a locus on chromosome 12 from 36.8 to 38.6 Mb with 36 markers reaching genome-wide significance (P(genome) = 0.00001-0.026). This study suggests that a major locus on chromosome 12 harbors genetic variations affecting the development of intervertebral disc calcification in Dachshund.

Herniation of the intervertebral disk is a common cause of neurological dysfunction in the dog, particularly in the Dachshund. Using the Illumina CanineHD BeadChip, we have previously identified a major locus on canine chromosome 12 nucleotide positions 36,750,205–38,524,449 that strongly associates with intervertebral disk calcification in Danish wire-haired Dachshunds. In this study, targeted resequencing identified two synonymous variants in MB21D1 and one in the 5′-untranslated region of KCNQ5 that associates with intervertebral disk calcification in an independent sample of wire-haired Dachshunds. Haploview identified seven linkage disequilibrium blocks across the disease-associated region. The effect of haplotype windows on disk calcification shows that all haplotype windows are significantly associated with disk calcification. However, our predictions imply that the causal variant(s) are most likely to be found between nucleotide 36,750,205–37,494,845 as this region explains the highest proportion of variance in the dataset. Finally, we develop a risk prediction model for wire-haired Dachshunds. We validated the association of the chromosome 12 locus with disk calcification in an independent sample of wire-haired Dachshunds and identify potential risk variants. Additionally, we estimated haplotype effects and set up a model for prediction of disk calcifications in wire-haired Dachshunds based on genotype data. This genetic prediction model may prove useful in selection of breeding animals in future breeding programs.

Background: A genome-wide scan in unrelated US Caucasians identified rs7001819 upstream of farnesyl-diphosphate farnesyltransferase 1 (FDFT1) and multiple variants within catenin (cadherinassociated protein), β-like 1 (CTNNBL1) to associate strongly with body mass index (BMI). The most significantly associating variants within CTNNBL1 including rs6013029 and rs6020846 were additionally confirmed to associate with morbid obesity in a French Caucasian case-control sample. The aim of this study was to investigate the impact of these three variants on obesity, through analyses of obesity-related quantitative traits, and case-control studies in large study samples of Danes.