RESUMO
Genome-wide association (GWA) studies identified novel gene variants that are associated with type 2 diabetes. However, results were not always consistent across different populations. Thus, the aims of this study were (i) to replicate findings from previous GWA studies in mainly Northern European populations using data from the German KORA 500 K diabetes project and (ii) to assess the impact of BMI on associations between single nucleotide polymorphisms (SNPs) and type 2 diabetes. The KORA 500 K diabetes project includes 433 cases with validated type 2 diabetes and 1 438 nondiabetic controls from two population-based KORA surveys. Genotyping was performed using the Affymetrix GeneChip Human Mapping 500 K Array Set. We investigated associations between SNPs and type 2 diabetes in 10 genes that have been reported to increase the risk of type 2 diabetes or were in complete or near-complete linkage disequilibrium with these variants. SNPs in the CDKAL1 gene showed the strongest association with type 2 diabetes [range of age and sex-adjusted odds ratios (OR): 1.30-1.39, p-values 0.0008-0.0004]. In addition, we found evidence for association of SNPs in the genes PPARG, IGF2BP2, HHEX, TCF7L2, and FTO with type 2 diabetes in the same directions as previously described (p<0.05), but not for WFS1, CDKN2A/B, KCNJ11, or EXT2. Adjustment for BMI slightly strengthened the link between CDKAL1 and type 2 diabetes, but had almost no impact on the other associations. We conclude that gene variants of CDKAL1, PPARG, IGF2BP2, HHEX, TCF7L2, and FTO predispose to type 2 diabetes in the German KORA 500 K study population. These associations appear to be independent of BMI.
Assuntos
Quinase 5 Dependente de Ciclina/genética , Diabetes Mellitus Tipo 2/genética , Predisposição Genética para Doença , PPAR gama/genética , Polimorfismo de Nucleotídeo Único/genética , Proteínas de Ligação a RNA/genética , População Branca/genética , Adulto , Idoso , Índice de Massa Corporal , Inibidor de Quinase Dependente de Ciclina p15/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Feminino , Alemanha , Proteínas de Homeodomínio/genética , Humanos , Masculino , Proteínas de Membrana/genética , Pessoa de Meia-Idade , N-Acetilglucosaminiltransferases/genética , Canais de Potássio Corretores do Fluxo de Internalização/genética , Fatores de Transcrição TCF/genética , Proteína 2 Semelhante ao Fator 7 de Transcrição , Fatores de Transcrição/genética , tRNA MetiltransferasesRESUMO
This article considers the problem of comparing several treatments (dose levels, interventions, etc.) with the best, where the best treatment is unknown and the treatments are ordered in some sense. Order relations among treatments often occur quite naturally in practice. They may be ordered according to increasing risks, such as tolerability or safety problems with increasing dose levels in a dose-response study, for example. We tackle the problem of constructing a lower confidence bound for the smallest index of all treatments being at most marginally less effective than the (best) treatment having the largest effect. Such a bound ensures at confidence level 1 -alpha that all treatments with lower indices are relevantly less effective than the best competitor. We derive a multiple testing strategy that results in sharp confidence bounds. The proposed lower confidence bound is compared with those derived from other testing strategies. We further derive closed-form expressions for power and sample size calculations. Finally, we investigate several real data sets to illustrate various applications of our methods.