CHICAGO --- Researchers from Northwestern University Feinberg School of Medicine have discovered a link between sporadic and familial forms of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease also known as Lou Gehrig's disease.
Researchers found that a protein called FUS forms characteristic skein-like cytoplasmic inclusions in spinal motor neurons in most cases of ALS. Mutations in this gene have been previously linked to a small subset of familial ALS cases. Researchers thus linked a rare genetic cause to most cases of ALS, clearing the way for rational therapy based on a known molecular target.
The study was recently published online in the Annals of Neurology.
ALS is a disease in which muscle-controlling nerve cells in the brain and spinal cord (motor neurons) die, resulting in rapidly progressive paralysis and death usually within three to five years of the onset of symptoms. Most cases of ALS are of unknown etiology and appear as sporadic ALS. About 5 to 10 percent of ALS cases are familial. Some forms of familial ALS are caused by genetic mutations in specific genes. Mutations in the Cu/Zn superoxide dismutase gene (SOD1) account for approximately 20 percent of familial ALS cases. Mutations in the TAR DNA-binding protein gene (TDP43) and FUS gene occur in about 4 to 5 percent of the familial ALS cases. Altogether, mutations in specific genes have been identified in about 30 percent of familial ALS cases. In contrast to familial ALS, the etiology and the pathogenic mechanisms underlying sporadic ALS -- 90 percent of all ALS -- has remained largely unknown. Understanding the causes and pathogenic mechanisms of sporadic ALS is the major challenge in this disease.
For this study, researchers examined the post-mortem spinal cords and brains of 100 cases, 78 with ALS and 22 in a control group. They found FUS pathology in the spinal cords of all the ALS cases, except for a few cases with SOD1 mutation
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