title: The common rs9939609 variant of the fat mass and obesity-associated gene is associated with obesity risk in children and adolescents of Beijing, China.
abstract: BACKGROUND
  Previous genome-wide association studies for type 2 diabetes susceptibility genes have confirmed that a common variant, rs9939609, in the fat mass and obesity associated (FTO) gene region is associated with body mass index (BMI) in European children and adults. A significant association of the same risk allele has been described in Asian adult populations, but the results are conflicting. In addition, no replication studies have been conducted in children and adolescents of Asian ancestry.
  
  
  METHODS
  A population-based survey was carried out among 3503 children and adolescents (6-18 years of age) in Beijing, China, including 1229 obese and 2274 non-obese subjects. We investigated the association of rs9939609 with BMI and the risk of obesity. In addition, we tested the association of rs9939609 with weight, height, waist circumference, waist-to-height ratio, fat mass percentage, birth weight, blood pressure and related metabolic traits.
  
  
  RESULTS
  We found significant associations of rs9939609 variant with weight, BMI, BMI standard deviation score (BMI-SDS), waist circumference, waist-to-height ratio, and fat mass percentage in children and adolescents (p for trend = 3.29 x 10-5, 1.39 x 10-6, 3.76 x 10-6, 2.26 x 10-5, 1.94 x 10-5, and 9.75 x 10-5, respectively). No significant associations were detected with height, birth weight, systolic and diastolic blood pressure and related metabolic traits such as total cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol and fasting plasma glucose (all p > 0.05). Each additional copy of the rs9939609 A allele was associated with a BMI increase of 0.79 [95% Confidence interval (CI) 0.47 to 1.10] kg/m2, equivalent to 0.25 (95%CI 0.14 to 0.35) BMI-SDS units. This rs9939609 variant is significantly associated with the risk of obesity under an additive model [Odds ratio (OR) = 1.29, 95% CI 1.11 to 1.50] after adjusting for age and gender. Moreover, an interaction between the FTO rs9939609 genotype and physical activity (p < 0.001) was detected on BMI levels, the effect of rs9939609-A allele on BMI being (0.95 +/- 0.10), (0.77 +/- 0.08) and (0.67 +/- 0.05) kg/m2, for subjects who performed low, moderate and severe intensity physical activity.
  
  
  CONCLUSIONS
  The FTO rs9939609 variant is strongly associated with BMI and the risk of obesity in a population of children and adolescents in Beijing, China.
authors.affiliation: Department of Epidemiology, Capital Institute of Pediatrics, 2 Ya Bao Road, 100020 Beijing China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xi
authors.forename: Yue
authors.initials: Y
authors.lastname: Shen
authors.forename: Meixian
authors.initials: M
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Zhao
authors.forename: Lijun
authors.initials: L
authors.lastname: Wu
authors.forename: Hong
authors.initials: H
authors.lastname: Cheng
authors.forename: Dongqing
authors.initials: D
authors.lastname: Hou
authors.forename: Klaus
authors.initials: K
authors.lastname: Lindpaintner
authors.forename: Lisheng
authors.initials: L
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Mi
authors.forename: Xingyu
authors.initials: X
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; D002648:Child; D002681:China; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009765:Obesity / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011506:Proteins / Q000235:genetics*; D012307:Risk Factors; D012727:Sex Characteristics
chemical_list: D011506:Proteins; D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; C526492:FTO protein, human