Oct. 30, 1997 Good results in preliminary studies of a potential diagnostic test for amyotrophic lateral sclerosis (ALS) have led Johns Hopkins scientists to call for an expanded trial immediately. At this week's meeting of the Society for Neuroscience in New Orleans, Hopkins neurologist Jeffrey Rothstein, M.D., Ph.D., is asking physicians "to send us cerebrospinal fluid from their patients to give us a larger sample to evaluate the test."
Currently, diagnosis of ALS, also known as Lou Gehrig's disease, is indirect, requiring months of tests to exclude other diseases. "During this time, motor nerve cells are dying," says Rothstein. "If our new test works, doctors can check for ALS at the first sign of ALS-like symptoms and begin treatment much earlier."
A drug called riluzole, approved in 1995 by the Food and Drug Administration, can slow the disease, although it is unable to halt it. Other drugs are under study, and experts believe that earlier application of those treatments could significantly improve the quality of patients' lives.
The test is based on findings by Rothstein and his colleagues last year that about 65 percent of ALS patients have mutations involving abnormal or mutant forms of EAAT2, a protein that normally deactivates and recycles glutamate. Glutamate is a chemical nerve cells use to send messages. ALS patients often have little or no EAAT2 in certain areas of the brain and spinal cord, creating an excess of glutamate that kills the nerves that control muscles.
The usual result is gradually increasing paralysis and death in two to five years. Nearly 30,000 people currently have the disease. It is largely sporadic, and there are no laboratory tests useful for its early diagnosis.
To test the mutations' value as a way of detecting ALS, Hopkins researchers looked for it in the cerebrospinal fluid of 18 ALS patients and 38 non-ALS patients with multiple sclerosis, stroke, headache or other problems. They found it in 12 of the 18 ALS patients, and none of other patients.
"That's a pretty good rate, and it matches what we find in brain tissue post-mortem, but to get a real feel for the potential of this test we need to see what it can do in a much larger population sample," says Rothstein.
The studies that identified EAAT2 abnormalities were funded in part by the Cal Ripken/Lou Gehrig Fund for Neuromuscular Research, a fund for research into ALS and other neuromuscular diseases created in 1995 when Ripken broke Gehrig's long-standing record for consecutive games played. Additional funding comes from the National Institutes of Health, the Muscular Dystrophy Association, and the ALS Association.
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