Navigenics, of Redwood Shores, CA, is developing a genetic test to help customers assess and respond to their risks of contracting numerous illnesses, including Alzheimer's, type 2 diabetes, rheumatoid arthritis, and breast cancer. The genome-wide scan targets 20 diseases so far.

The company says that this year it will begin offering the test directly to consumers for $2,500, joining competitors deCode Genetics of Iceland and 23andMe of Mountain View, CA, both of which recently began offering personal genetic tests for under $1,000. Navigenics also says that it plans to follow up customers' test results with extensive interpretation from on-staff genetic counselors.