Genetic linkage refers to genes and other genetic markers generally being inherited together because of their location on the same chromosome. Type 2 diabetes is a well-known disease that has largely affected a large percentage of the United States population as the obesity rate and other health-related problems continue to rise. Through linkage analysis, researchers were able to identify diabetes risk genes. These studies revealed that two genes, CAPN10 and TCF7L2, were discovered by linkage analysis. While the link between gene CAPN10 and type 2 diabetes is still unclear, the link between gene TCF7L2 and type two diabetes appeared significantly stronger. Specifically, the TCF7L2 gene was genetically mapped in different populations worldwide: the Mexican-American population, Icelandic population, Danish cohorts, and the United States population. Because this specific gene (TCF7L2) linkage was found across multiple ethnic groups, this gene is identified as the most type 2 diabetes risk gene.