Medical News Today (Sept. 22, 2011)-Frontotemporal dementia and amyotrophic lateral sclerosis, also known as Lou Gehrig's disease -- two fatal neurodegenerative disease with distinct but sometimes overlapping symptoms -- are triggered by a common mutation in many cases, according to researchers who say they have identified the mutated gene.
In the study, reported in the September 21 online issue of Neuron, the scientists described the discovery of a genetic mutation that is accountable for almost 12 percent of familial FTD and more than 22 percent of familial ALS samples studied.
They also report that the defect is the strongest genetic risk factor found to date for the more common, non-inherited, sporadic forms of these diseases. It was found in 3 percent of sporadic FTD and 4 percent of sporadic ALS samples in the largest clinical patient series.
The study was led by scientists at the Mayo Clinic in Florida, in collaboration with researchers at UCSF, the University of British Columbia and UCLA. The finding emerged from the identification and study of a family stricken by both ALS and FTD, reported last year. In that study, led by the UCSF scientists and published in the Journal of Neurology, Neurosurgery and Psychiatry, the researchers honed in on the region in which the gene was located.
"Both clinically and at the molecular level this discovery is going to significantly improve our understanding of these diseases," said co-author Adam Boxer, MD, PhD, of the UCSF Memory and Aging Center, the lead author on the 2010 paper. The discovery makes it possible to develop a diagnostic test for the mutation, as well as to create animal models that may be used to help unravel the molecular mysteries connecting the mutation to the diseases, he said.
In the current study, a detailed molecular genetic characterization of the family that Boxer described was done in the laboratory of senior author Rosa Rademakers, PhD, from the Mayo Clinic. She and colleagues identified the gene and the specific mutation within it.
The mutation consists of from hundreds to thousands of extra copies of a six-letter DNA sequence GGGGCC strung end to end within a region of human chromosome nine. The mutation occurs within a gene of unknown function called C9ORF72.
After identifying the mutation, the Mayo researchers searched for it in DNA from other patients with both familial and sporadic forms of the diseases, where they found the strong associations.
FTD is characterized by disturbances in decision making, language skills, behavior and emotional expression, and is as common as Alzheimer's disease in people younger than 65, according to Boxer. ALS is a neuromuscular disease, leading to muscle paralysis and respiratory failure, often within three to five years. However, it is not unusual for patients diagnosed with one of the two diseases to exhibit symptoms of the other.
To read more about ALS and FTD, please click the above title.
No comments:
Post a Comment