February 2, 2004
Diagnosing and treating multiple sclerosis could become easier thanks to a simple genetic blood test that could end the need for such invasive procedures as spinal taps.
Researchers have demonstrated that DNA microarrays, which measure the activity of thousands of genes, can help predict the development of the disease.
"Our study was not designed to study response to treatment and predict course, however it does provide support to the notion that microarray results could be used to predict course of disease and, potentially, therapeutic response," says Naftali Kaminski of the University of Pittsburgh Medical Center in Pennsylvania.
Little understood disease
Multiple sclerosis is a little understood disorder of the nerve fibers of the brain and spinal cord.
What scientists do know is that myelin, a substance that normally insulates nerves from damage and speeds electrical conduction, is replaced by scarring—"sclerosis."
Depending on which nerve fibers are affected, sufferers can have problems ranging from weakness and clumsiness to numbness, visual disturbances and even emotional and intellectual changes.
In some, the disease progresses to a stage of severe debilitation, either slowly or rapidly. In others the disease manifests itself in cycles of relapse and remission.
Researchers would like to predict the course of the disease, both to inform patients and to make better use of minimally invasive treatments.
Kaminski and colleagues turned their attention to immune system cells called lymphocytes that circulate in the bloodstream and are involved in the destruction of myelin.
"In this study, we wanted to determine whether gene expression patterns in peripheral blood contain information regarding a disease that is confined to the nervous system," says Kaminski.
Other researchers have previously used DNA microarrays to compare lymphocyte gene activity in people with multiple sclerosis with that in healthy subjects.
Kaminski and colleagues went a step further by adding subjects in relapse. They also took advantage of more advanced technology, including microarrays that can measure activity in three times as many genes.
Applying advanced computer analysis methods, the researchers found significant differences in more than 1,000 genes between control subjects and multiple sclerosis sufferers, regardless of their disease status.
They also identified more than 200 genes whose activity changed—becoming more or less active—during disease flare-ups.
Further experiments will seek to determine whether microarrays can help predict the course of disease or when someone in remission will suffer a relapse.
The study also pinpoints hundreds of genes—some of them already being studied in other contexts—to examine for their role in multiple sclerosis.
If researchers can determine how they turn lymphocytes against myelin, drugs could be targeted to control their activity.
The research is reported in the Annals of Neurology.
Copyright © 2004, Betterhumans