title: The combined effect of the T2DM susceptibility genes is an important risk factor for T2DM in non-obese Japanese: a population based case-control study.
abstract: BACKGROUND
  Type 2 diabetes mellitus (T2DM) is a complex endocrine and metabolic disorder. Recently, several genome-wide association studies (GWAS) have identified many novel susceptibility loci for T2DM, and indicated that there are common genetic causes contributing to the susceptibility to T2DM in multiple populations worldwide. In addition, clinical and epidemiological studies have indicated that obesity is a major risk factor for T2DM. However, the prevalence of obesity varies among the various ethnic groups. We aimed to determine the combined effects of these susceptibility loci and obesity/overweight for development of T2DM in the Japanese.
  
  
  METHODS
  Single nucleotide polymorphisms (SNPs) in or near 17 susceptibility loci for T2DM, identified through GWAS in Caucasian and Asian populations, were genotyped in 333 cases with T2DM and 417 control subjects.
  
  
  RESULTS
  We confirmed that the cumulative number of risk alleles based on 17 susceptibility loci for T2DM was an important risk factor in the development of T2DM in Japanese population (P<0.0001), although the effect of each risk allele was relatively small. In addition, the significant association between an increased number of risk alleles and an increased risk of T2DM was observed in the non-obese group (P<0.0001 for trend), but not in the obese/overweight group (P=0.88 for trend).
  
  
  CONCLUSIONS
  Our findings indicate that there is an etiological heterogeneity of T2DM between obese/overweight and non-obese subjects.
authors.affiliation: Laboratory of Human Genetics, School of Food and Nutritional Sciences, Graduate School of Nutritional and Environmental Sciences, Global COE Program, University of Shizuoka, Shizuoka 422-8526, Japan. kobayasi@u-shizuoka-ken.ac.jp
authors.forename: Kimiko
authors.initials: K
authors.lastname: Yamakawa-Kobayashi
authors.forename: Maki
authors.initials: M
authors.lastname: Natsume
authors.forename: Shingo
authors.initials: S
authors.lastname: Aoki
authors.forename: Sachi
authors.initials: S
authors.lastname: Nakano
authors.forename: Tomoko
authors.initials: T
authors.lastname: Inamori
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Kasezawa
authors.forename: Toshinao
authors.initials: T
authors.lastname: Goda
mesh_terms: D000328:Adult; D000483:Alleles; D044466:Asian People / Q000235:genetics*; D015992:Body Mass Index; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000235:genetics*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D005838:Genotype; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics; D016017:Odds Ratio; D050177:Overweight; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors