An F.D.A. spokeswoman said that if doctors place orders, testing companies that operate their own laboratories do not need F.D.A. approval to offer their tests.

Some testing experts question whether Color can provide testing as inexpensively as it claims. While the actual sequencing might be done for less than $250, that is only part of the cost, which also involves interpretation and working with patients and doctors, they say. Other companies generally charge at least $1,500 for complete analyses of the BRCA genes or for multigene tests.

But Dr. Gil said Color has highly automated its processes and will even offer genetic counseling to women. He said the company chose the saliva test rather than a blood one because it’s easier for users but still accurate. Women send the saliva sample to Color for testing.

Dr. Gil received a doctoral degree in biology at the Massachusetts Institute of Technology, studying a cancer gene. But he has spent much of his career at Google and Twitter. The company’s president, Othman Laraki, also worked at Google and Twitter.

Color’s backers — it says it has raised about $15 million — are mainly from the world of high tech rather than life sciences. Its lead investors are the venture capital firms Khosla Ventures and Formation 8. Individual investors include Laurene Powell Jobs, the widow of Steve Jobs; Susan L. Wagner, a co-founder of the investment firm BlackRock; Padmasree Warrior, the chief technology and strategy officer at Cisco; and Jerry Yang, co-founder of Yahoo.

Dr. Offit of Sloan Kettering said that even Myriad, which long had a monopoly on BRCA testing and has the most data, has reported having a 2 percent rate of variants of unknown significance, meaning 2 percent of the time it cannot tell if a variant in a gene increases the risk of cancer or is benign. Other companies might have higher rates. And the rates for some other, less-well-studied genes can be 20 or 30 percent, he said.

The entire testing industry is now scrambling to pool data to lower that rate, and in some cases to catch up to Myriad, which has kept much of its data proprietary as a competitive advantage. Various data-sharing efforts are already underway, including by ClinVar and the BRCA Challenge.