Type 2 diabetes mellitus (T2D) affects approximately 21 million individuals in the U.S., or almost 10% of the U.S. adult population. Because diabetes is determined by both genetic and environmental factors, a better understanding of the etiology of diabetes requires a careful investigation of gene-environment interactions. The Nurses' Health Study (NHS) and Health Professionals' Follow-up Study (HPFS) are well-characterized cohort studies of women and men for whom stored blood and DNA samples are available as well as detailed information on dietary and lifestyle variables. The major goals of the project include: 1. To conduct a GWA analysis among 3,000 cases of T2D and 3,000 healthy controls in NHS/HPFS cohorts. 2. To use information on the joint effects of genes and a list of carefully selected environmental exposures at the initial screening stage to test gene-environment interactions. This approach optimizes our power to detect variants that have a sizeable marginal effect and those with a small marginal effect but a sizeable effect in a stratum defined by an environmental exposure. For this analysis, we have developed a joint test of genetic marginal effect and gene-environment interaction. This flexible two-degree-of-freedom test generally provides greater power than standard methods and has the potential to uncover both marginal genetic effects and stratum-specific effects. The Version 1 (v1) dbGaP release of data from the GENEVA Diabetes Study (NHS/HPFS) includes data from the NHS only. The Version 2 (v2) dbGaP release includes data from both the NHS and HPFS. This study is part of the Gene Environment Association Studies initiative (GENEVA, <a href="http://www.genevastudy.org">http://www.genevastudy.org</a>) funded by the trans-NIH Genes, Environment, and Health Initiative (GEI). The overarching goal is to identify novel genetic factors that contribute to type 2 diabetes mellitus through large-scale genome-wide association studies of well-characterized cohorts of nurses and health professionals. Genotyping was performed at the Broad Institute of MIT and Harvard, a GENEVA genotyping center. Data cleaning and harmonization were done at the GEI-funded GENEVA Coordinating Center at the University of Washington.

GENEVA Diabetes Study (NHS/HPFS)

Diabetes Mellitus, Type 2 study with SNP Genotypes (Array), SNP Genotypes (imputed) data on dbGaP (6,033 participants)