The 10 intrepid volunteers who signed up for George Church’s Personal Genome Project (PGP) will soon have a lot of company. According to a report from Northwestern University, 13,000 people are in the process of enrolling in the project, which involves having the coding region of your genome sequenced, and then sharing it, along with medical records and other information, in an open-access database for analysis by geneticists and others around the world.

Here’s a brief description of the project from a piece I wrote last October.

Headed by Harvard University genomics pioneer George Church, the project aims to capitalize on rapid improvements in gene-sequencing technologies to better understand human health and disease. The PGP will serve as both a technological and an ethical test bed, assessing new methods of reading, sorting, and analyzing DNA, and highlighting societal issues that could spring up in the era of personal genomics–most notably, the privacy of genetic information.

Over the past year, the first 10 volunteers, including the linguist Steven Pinker, the entrepreneur Esther Dyson, and Church himself, have surrendered blood and skin samples, subjected themselves to medical examinations, and filled out extensive personal and medical questionnaires. Scientists have since gone to work sequencing their DNA, and an initial analysis of a portion of their genomes will be released today.

The data will be deposited into a database that Church and his collaborators hope will serve as a public resource for personal-genomics research, allowing other scientists to search for specific genetic variations linked to diseases and other traits. The researchers aim to grow the database rapidly and are now enrolling the next wave of volunteers, possibly as many as 100,000 participants. They are also creating cell lines from participants’ tissue samples, which they will make available for research.

Volunteers have to pass an online test to make sure that they understand exactly what participation entails–such as finding out you are at risk for a genetic disease.

For more on the PGP, check out a feature I wrote earlier this year on the challenges of interpreting the huge amount of genomic information made possible by new sequencing technologies.

The first set of data–released to participants in October–hints at both the promise of sequencing and the current limitations of genetic analysis. John Halamka, CIO of Harvard Medical School and another one of the 10 original volunteers, learned that he carries a mutation for Charcot Marie-Tooth disease, an inherited neurological disorder. This rare variation would not have been found with existing SNP arrays. But since Halamka survived childhood unscathed, and only three other people in the world have been shown to carry that particular mutation, it’s hard to know what impact, if any, it has had on his health. Perhaps many people carry the variation with no ill effect, and the link between the disease and the mutation has been overstated. Or perhaps the gene has a broader impact than expected, raising the risk of other neurological diseases. (Or, as George Church notes, the finding may simply be an error.)

The greater the number of entries in the database, the easier it will be to understand a finding like Halamka’s. And in April 2008, Church’s team received approval from Harvard to expand the project from 10 to 100,000 participants. (Church plans to scale up slowly, multiplying the number of subjects by 10 each year.) This next phase will seriously test both the technology used to sequence the genomes and the strategies used to interpret the resulting data. As of November, about a year into the project, PGP scientists had gotten only about a fifth of the way through sequencing the coding regions of the original volunteers’ genomes. (Church plans to expand the PGP to the entire genome once sequencing becomes cheap enough.) If they’re to sequence thousands more genomes, sequencing technology will need to become as fast and robust as Church believes it can be.

And here’s a Q & A with Church, published soon after he announced the project.