Time between onset and symptoms could be targeted for therapy, study suggests,,
MONDAY, JUNE 15 (HealthDay News) -- Researchers now believe that ALS, or amyotrophic lateral sclerosis, starts well before its debilitating symptoms appear, a finding that they say could eventually lead to an effective treatment.
Protein clumps in cells that show up only after damage has occurred, rather than at the onset of the disease, appear responsible for the paralyzing course of ALS (amyotrophic lateral sclerosis), according to University of Florida researchers.
The research team found that the formation of these clumps of defective proteins and cell matter, called "protein aggregates," actually signals that ALS is progressing at a rapid pace.
In ALS, nerve cells extending from the brain to the spinal cord and then to the muscles die off. Its cause is unknown, though an inherited defective gene is suspected in up to 20 percent of cases. Scientists thought it originated with malformed -- or "misfolded" -- proteins that malfunction and lead to the protein aggregates in the brain.
The ALS Association says that about 30,000 Americans have the disease, which is often referred to as Lou Gehrig's disease, after the renowned ballplayer who died of ALS.
The Florida researchers examined the gene that produces superoxide dismutase 1, or SOD1, an enzyme that fights off free radicals -- molecules that damage the body's cells. People with the inherited version of ALS have been found to have one of the 146 known mutations in the SOD1 gene.
In the online edition of Human Molecular Genetics, the researchers wrote that the SOD1 mutations most likely to cause the protein clumps were also linked to the disease's faster progression.
Another study, recently published online in the Proceedings of the National Academy of Sciences, found that mice genetically altered to have ALS experience cell damage well before protein aggregates start to appear, a time that coincides with telltale symptoms of the disease.
"As the disease enters the symptomatic stage in mice, the buildup of protein is rapid and dramatic," David Borchelt, director of the SantaFe HealthCare Alzheimer's Disease Research Center at the university's McKnight Brain Institute, where the studies took place, said in a university news release. "However, the formation of these aggregates is not the whole story. It is well-established that significant damage to the nervous system occurs well before the symptoms appear. The uncontrolled misfolding of SOD1 seems to be confined to the late stage of disease, which is when symptoms first appear, giving hope that treatments targeting this process could be beneficial."
The finding suggests that there may be significant time to treat ALS before the clumping and symptoms appear, signaling the quickening pace of progression. But this would require development of an accurate way to diagnose ALS before symptoms emerge.
"Blocking aggregation of these proteins could be a therapeutic target for individuals with this genetic mutation," Borchelt said. "Right now, there is little that can be done to help these patients."
The ALS Association has more about ALS.
-- Kevin McKeever
SOURCE: University of Florida, news release, June 8, 2009
All rights reserved