And then there were four.

Today a fourth major online genetic testing start-up was announced: the San Diego-based Pathway Genomics. Like the Big Three--23andme, deCodeme, and Navigenics--Pathway is hoping that if they build it, the people will come.

So far, it's unclear if they will anytime soon. None of the current companies have released sales figures, suggesting the response so far may not be huge. This is not unusual with an early stage technology, though this has hardly stopped Pathway from throwing their genetic proclivities into the fray.

Many experts remain skeptical that the science of determining genetic risk factors for diseases such as cancer is ready to be applied to individual consumers. But a buzz has been gathering for some time that genomics--and its close-cousins proteomics and envirogenomics--will one day revolutionize medicine, and how we view ourselves.

The Big Four and their investors-- hich have included Google, Genentech, and venture powerhouses such as Kleiner Perkins--are assuming this will happen sooner rather than later. Pathway also has major league financial backing, including investment from the Founders Fund--led by former Paypal co-founders Peter Theil, Ken Howery, and Luke Nosek, and Napster co-founder Sean Parker.

Many of the services Pathway is proffering are available on the other sites. Like the others, the company is offering genetic counseling for customers, though for a small fee. Pathway also plans to offer social networking on its site. "We have investors and founders involved in Facebook and Linked-in, so we think this is important," says CEO and founder James Plante.

Yet the company is different from its competitors in several ways:

· Pathway is cheaper, offering ancestry testing for $199 and health markers for $249. Ordering both packages costs a discounted $348. The next cheapest product is from 23andme, which charges $399 for its FullEdition. 23andme also offers a "research revolution" edition for $99 for people with certain diseases--migraines, psoriasis, epilepsy, and others--who agree to participate in a research study. DeCodeme's main product costs $985; Navigenics has just reduced their price to $999. Each service has differences--check my "You 2.0" series analyzing the three sites on Portfolio.com, and check out the sites themselves for the latest changes.

· Pathway has invested in its own government-approved lab to test their customer's DNA. deCodeme in Iceland has its own lab, too, although Pathway is the only company with three major DNA genotyping hardware systems--from Illumina, Affymetrix, and Sequenom. This provides Pathway customers with more gene markers than its rivals. "We are technologically agnostic," says Pathway Chief Scientific Officer David Becker.

· Having a lab and the technicians and scientific personnel to man it makes Pathway less a software play than some of its rivals - though deCodeMe in Iceland remains the company with the most scientific depth as a decade-old drug and genomics company that has discovered some of the more important genetic markers for disease that are used by all of the other companies.

· Pathway is also offering slightly more results on more traits than even 23andme, which previously held the record. They are planning to provide genetic results for over 90 disease traits and, for the first time, DNA risk factors for several medications that can cause side effects or neutralize a drug's effectiveness.

· The company is asking customers to provide family history information that they say will be integrated into risk factor profiles. "You might have a high risk for a rare genetic disorder, but if you don't have this disease in your family history, this is not a high risk," says Becker. He adds that Pathway will not offer over-all scores for a customer's risk for disease. "We don't think there is enough information in single genetic markers to come up with that kind of score," he says.

The company has not yet revealed all the details of their product--how they will analyze results and will deal with the preliminary nature of some of the information for example. But Becker says they will release more information in the next few weeks.

Pathway has promised to let me test-drive their product. After I get my results, I'll let you know how it works and how it compares to the other main DNA testing sites. Much of the promise of consumer genetics remains in the future, though the arrival of Pathway offers another signal that even if the DNA gold rush isn't quite here yet, it is coming.