Abnormal Protein Potential Biomarker for ALS and FTD

Identification of abnormal protein may help diagnose and treat Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease and frontotemporal dementia (FTD).

Investigators have discovered an abnormal protein that first forms as a result of genetic abnormalities and later builds up in the brains of many patients with either disease. These investigators are beginning to recognize ALS and FTD as part of a spectrum disorder with overlapping symptoms.

By analyzing brain tissue from patients with ALS or FTD, Dr. Petrucelli, chair of neuroscience at Mayo Clinic in Florida (Jacksonville, FL, USA) and his team discovered that the abnormal protein, which they call C9RANT, is generated as a result of repeat expansions of nucleotides in the noncoding region of the C9ORF72 gene. These expansions are the most common cause of ALS and FTD. "Simply put, an error in the highly regulated cellular process through which proteins are generated causes the abnormal production of C9RANT," explained Dr. Petrucelli.

The scientists discovered the protein C9RANT after creating a novel antibody to specifically detect it. The ability to detect C9RANT in individuals' cerebrospinal fluid (CSF) may provide a valuable diagnostic and prognostic tool for identifying patients carrying the C9ORF72 repeat expansion and for then tracking the progression of the disease in these at-risk individuals.

Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, and frontotemporal dementia (FTD) are devastating neurodegenerative diseases with no effective treatment. "Although it remains to be shown whether C9RANT is causing the cell death or toxicity associated with disease symptoms, our discovery offers a potential target to prevent neuronal loss in patients carrying the C9ORF72 repeat expansion," said Dr. Petrucelli.

These studies were reported online in the February 12, 2013, Cell Press journal Neuron. The investigators described an abnormal protein that first forms as a result of genetic abnormalities and later builds up in the brains of many patients with ALS or FTD.

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Mayo Clinic in Florida