The new test provides a clear look at defective genes often hidden from conventional tests. People with genes linked to a disease aren't guaranteed to fall ill. In a study appearing in today's Nature , Vogelstein's team compared the new test with established screening for colon cancer genes. Looking at 22 men with inherited colon cancer, the traditional test missed genes associated with the disease in 12 cases. Researchers identified genes responsible for those cases five years ago, but many established genetic tests suffer from inaccuracy.
Human genes come in pairs, called alleles, contributed by both parents.
Conventional tests often fail to reveal mutant genes that lead to cancer because normal alleles obscure the defective partner. To get at the defective genes, Vogelstein's team jolted a sample of each patient's white blood cells with electricity, fusing them to a line of specially created mouse cells. The mouse cells' genetic material pried the colon cancer alleles apart and recombined with them. Next, the researchers examined the resultant cells using regular genetic analysis. Johns Hopkins University has licensed the test to GMP Inc., a Fort Lauderdale biotechnology firm that plans to offer it this summer for colon cancer and other diseases.