Recently, though, scientists have begun to figure out how to identify the presence of specific diseases by reading the precise cocktail of proteins in a patient’s blood. Proteins perform essential functions–ridding the body of toxins, fighting infections and metabolizing food. When we’re ill, proteins are secreted into our blood. Some of these are hormones or antibodies; others come from damaged cells or invading bacteria and viruses. There’s been so much progress of late in identifying these so-called biomarkers done by taking blood from patients with a disease and sifting through to see what’s there–that scientists believe it may soon be possible to devise a universal diagnostic test that would be able to detect a wide range of diseases, and do so more reliably and conveniently than current methods.
Biomarkers have been around for some time. High levels of the enzyme amylase, for example, are a good indicator of pancreatitis, and other enzymes predict acute heart attacks. Scientists have searched for other biomarkers, but, it turns out, few proteins correspond neatly to specific diseases.
Dr. Adrian Woolfson and his colleagues at Cambridge University took a different approach. Rather than match single biomarkers to individual diseases, they started analyzing patterns of many biomarkers in the blood. After combing through hundreds of thousands of human proteins, they found 300 or so that can be used to flag most diseases. By measuring the level of each of these proteins, it’s possible to obtain a signature, like a bar code, unique to a specific disease. “We expect that there will be a revolution in diagnostics for all categories of disease in the future,” says Woolfson.
Much work must be done before the test is ready for clinical use. The University of Cambridge has recently licensed the technology to a biotech firm called ProteinLogic in Cambridge, which is building large databases of these protein “bar codes.” Computers then search the database looking for diagnostic patterns that provide the disease-specific bar code. The more samples in the database, the more accurate the system becomes.
The technology could be a boon to developing nations, where doctors are in short supply. Woolfson wants to develop a portable diagnostic kit that would be as disposable and easy to use as a home pregnancy test–Woolfson calls it a “doctor on a stick.” “Diagnostic tests will never replace doctors,” he says. But they may help poor communities and keep a lot of healthy people off the operating table.
