he team, known as the SIGMA (Slim Initiative in Genomic Medicine for the Americas) Type 2 Diabetes Consortium, performed the largest genetic study to date in Mexican and Mexican American populations, discovering a risk gene for type 2 diabetes that had gone undetected in previous efforts. People who carry the higher risk version of the gene are 25 percent more likely to have diabetes than those who do not, and people who inherited copies from both parents are 50 percent more likely to have diabetes. The higher risk form of the gene has been found in up to half of people who have recent Native American ancestry, including Latin Americans. The variant is found in about 20 percent of East Asians and is rare in populations from Europe and Africa.

The elevated frequency of this risk gene in Latin Americans could account for as much as 20 percent of the populations' increased prevalence of type 2 diabetes -- the origins of which are not well understood.