Amyotrophic lateral sclerosis (ALS;Lou Gehrigs disease) is a fatal neurodegenerative disorder that leads to rapidly progressive paralysis and respiratory failure. ALS is the third most common neurodegenerative disease in the Western World, and there are currently no effective therapies. Frontotemporal dementia (FTD) is the most common form of dementia in the population under the age of 65. An overlap between these two clinically distinct neurological diseases has long been recognized, but the molecular basis of this intersection was unknown. Recently, the Neuromuscular Diseases Research Unit (NDRU), a part of the Laboratory of Neurogenetics at the National Institute on Aging, identified the major genetic cause of both ALS and FTD. To do this, Dr. Traynor (chief of NDRU) organized a worldwide consortium, bringing together groups that had previously been competitors to focus their efforts towards identifying this gene. This was made possible by the next generation sequencing technologies available at the NIH. This innovative approach worked, and his group published the cause of chromosome 9-linked ALS/FTD in the journal Neuron in September 2011. In these cases, the disease is caused by a six base pair segment of DNA that is pathologically repeated over and over again, up to several thousand times. This so-called large hexanucleotide repeat disrupts the C9ORF72 gene located on chromosome 9. This is the most common genetic cause of both ALS and FTD identified to date, accounting for approximately 40% of all familial cases of ALS and FTD in European and North American populations. Further, Dr. Traynors group has shown that this mutation underlies about 8% of cases of sporadically occurring ALS and FTD that lack a family history. This represents the first time that a common genetic cause has been identified for the sporadic form of these diseases. In a separate publication in The New England Journal of Medicine, they have also shown that the same large hexanucleotide repeat expansion underlies 1% of Alzheimers disease cases. A one percent reduction in the number of AD cases would represent approximately $1 billion in healthcare cost savings annually. The discovery of the C9ORF72 hexanucleotide repeat expansion is a landmark discovery in our understanding of neurodegenerative disease. It has already greatly effected how these diseases are diagnosed, investigated and perceived, and provides a mechanistic link between two clinically distinct disorders, ALS and FTD. It also provides a distinct therapeutic target for gene therapy efforts aimed at ameliorating the disease, and such efforts are already well underway. In summary, we have been successful in identifying genetic variants important in the pathogenesis of FTD using next generation sequencing. Our data also helps to unify FTD and ALS into a single disease rubic that encompasses two of the major late-onset neurodegenerative diseases. Each of the two studies employed large cohorts of research subjects, and utilized the sequencing and genotyping facilities available within the Laboratory of Neurogenetics, NIA.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Investigator-Initiated Intramural Research Projects (ZIA)
Project #
1ZIAAG000934-05
Application #
8736653
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
5
Fiscal Year
2013
Total Cost
$341,958
Indirect Cost
Name
National Institute on Aging
Department
Type
DUNS #
City
State
Country
Zip Code
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Zhang, Ming; Xi, Zhengrui; Zinman, Lorne et al. (2015) Mutation analysis of CHCHD10 in different neurodegenerative diseases. Brain 138:e380
Diekstra, Frank P; Van Deerlin, Vivianna M; van Swieten, John C et al. (2014) C9orf72 and UNC13A are shared risk loci for amyotrophic lateral sclerosis and frontotemporal dementia: a genome-wide meta-analysis. Ann Neurol 76:120-33
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Donnelly, Christopher J; Zhang, Ping-Wu; Pham, Jacqueline T et al. (2013) RNA toxicity from the ALS/FTD C9ORF72 expansion is mitigated by antisense intervention. Neuron 80:415-28
Kaivorinne, Anna-Lotta; Bode, Michaela K; Paavola, Liisa et al. (2013) Clinical Characteristics of C9ORF72-Linked Frontotemporal Lobar Degeneration. Dement Geriatr Cogn Dis Extra 3:251-62

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