The approval last week is a turnaround for the agency, which had imposed a moratorium in 2013 on disease tests sold by the company, 23andMe, based in Mountain View, Calif. The decision is expected to open the floodgates for more direct-to-consumer tests for disease risks, drawing a road map for other companies to do the same thing.

The company will now be reporting telltale markers for 10 diseases. Most, such as factor XI deficiency, a blood clotting disorder, and Gaucher disease type 1, an organ and tissue illness, and celiac disease are rare. People who buy the $199 Ancestry and Health test from the company will automatically learn if they have mutations increasing their risk for those diseases.

Risk genes for Alzheimer's and Parkinson's are treated separately. Customers will have to specifically say that they want that information. The company's website offers links to genetic counselors for those who are weighing whether to be tested. If they want those results they will be included at no extra charge, although patients have to pay for the counseling separately.