The California start-up 23andMe sells genome scans directly to consumers, offering analysis of disease risk, ancestry and other genetic factors via its website. People who buy the scan can also opt to do a number of different surveys, on everything from specific disease symptoms to whether or not one sneezes in response to sunlight.

Part of the company’s mission since it was founded in 2007 has been to leverage the data it collects from customers for research, looking for associations between specific genetic variations and diseases and other traits. The technology used to run the scans is the same as that used in many genomics research studies, giving 23andMe a genetic database that is similar to a research consortium’s (though certainly not as carefully controlled and selected.)

According to Nicholas Eriksson, a scientist at 23andMe who presented his research at the Network Biology 2.0 conference in Cambridge this week, 35,000 people have taken 23andMe’s test, and about 20,000 of them have filled out one or more of its 40 surveys. The company has more than 400 ongoing studies searching for the genomic basis for everything from flu symptoms and asthma to dry mouth after taking the allergy drug zyrtec and euphoria after taking codeine.

Many scientists have been skeptical of whether a self-selected group of consumers and their self-reported information can generate reliable genetic associations. But the company will soon be publishing a paper in PLoS Genetics describing the results of early studies. Eriksson said they were able to replicate a number of variants that had been previously linked to cholesterol levels, obesity and diabetes. They also identified a number of new variants linked to somewhat less serious characteristics, including the ability to smell asparagus metabolites in urine. “There have been many years of debate in the very serious world of asparagus research over whether this is an issue of production or detection,” said Eriksson. Researchers linked this trait to an olfactory area on chromosome 1, suggesting the latter.

The company’s most significant effort to date has focused on Parkinson’s disease. (23andMe’s cofounder Anne Wojcicki is married to Google cofounder Sergey Brin, whose mother suffers from the disease and who learned he has a genetic risk factor after taking 23andMe’s test.) The company offered its test to Parkinson’s patients for $25, generating what Eriksson estimates is the largest Parkinson’s database in the world. They identified four genes that had already been linked to the disorder, as well as four to five novel genes that they are now trying to confirm in other populations. We did this study much more cheaply than those carried out at medical centers using more traditional methods, says Eriksson. “You have to be willing to give up some pristine data quality to get access to more people.”