Most health insurers are wary of genetics because, in most cases, it’s not yet clear how a particular genetic variation influences an individual’s health, or whether it should affect their care.

Now Kaiser Permanente, the nation’s largest nonprofit health plan, has announced that it’s finished the first phase of a massive project to compile genetic, medical, and environmental information for 100,000 of its members. Researchers also analyzed the length of participants’ telomeres—a molecule structure at the tip of the chromosome that has been linked to aging. This represents the largest telomere study to date.

The resulting data, gathered in collaboration with the University of California, San Francisco, will soon be available to outside researchers who study how different genetic and environmental factors influence disease. It took about 15 months for the team to collect and analyze the genomes of 100,000 people ranging in age from 18 to 107. The team used gene microarrays—small chips designed to quickly detect hundreds of thousands of genetic variations across the genome.

While genetic studies have been done on this scale before, they focused on one or a few diseases, such as diabetes and heart disease. The Kaiser project is unusual in that it includes years of comprehensive medical information—including blood-test results, medications, and other conditions—in the form of electronic health records. (Kaiser was one of the earliest adopters of electronic medical records in the United States.)

“The computerized data goes back 15 years,” says Neil Risch, a statistical geneticist at UCSF who co-led the study.  “It’s not like we have 100,000 blood-pressure measurements—it’s closer to a million.” By combining that information with prescriptions, for example, researchers could examine how genetics influence blood pressure and the effectiveness of medication.

Researchers will also incorporate environmental data, such as air-quality and water-quality records, based on knowledge of where participants lived and when.

Because the average age of the participants in the study is 65, “we think some of the most interesting initial questions will relate to aging,” says Cathy Schaefer, executive director of the Kaiser Permanente Program on Genes, Environment, and Health, and a co-leader on the project. “Specifically, are there genetic and environmental influences that lead to people living to a ripe old age without serious problems?”

Researchers will continue to follow participants as long as they continue to receive health care from Kaiser. They can examine, for example, how accurately telomere length can predict longevity or healthy aging.

Genetic studies such as these have often raised privacy issues—the concern is that individual participants could be identified and their data misused. In this case, because the health-plan provider is involved in the research, the fear is that Kaiser could use genetic information to alter rates or drop some members. But this type of discrimination is outlawed by the Genetic Information Non-Discrimination Act, passed in 2008. In addition, research participants’ information has special protection under the Health Insurance Portability and Accountability Act.

Patrick Taylor, a fellow at Harvard Law School’s Center for Health Law Policy, Biotechnology, and Bioethics, says he is not concerned about privacy issues in this case, in part because the project has oversight from the National Institutes of Health. (The project was funded by a two-year $24.8 million grant from the NIH.)  In addition, Kaiser has a long history of commitment to its members, says Taylor, who has studied the organization.