Researchers have identified the genetic anomaly that can makes some forms of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) run in families. The scientists, who included researchers from the National Institutes of Health (NIH) as well as from a number of international institutions, have identified a genetic mutation that accounts for approximately 50% of the familial FTD and ALS cases that are found in the Finnish population and more than 33% of familial ALS in other European groups. Additionally, these genetic mutations were found in Finnish people who have the more common form of ALS.
As I noted in an earlier sharepost, FTD (which is also known as Pick’s disease) is an umbrella term that is used for a group of disorders that affect the frontal and temporal lobes of the brain. These areas are generally associated with a person’s personality, behavior and language. This type of dementia, which strikes earlier than Alzheimer’s disease and results in death in a period of approximately eight years, is the most common type in people who are younger than 60 years old. ALS, which is often called “Lou Gehrig’s Disease,” is a progressive neurodegenerative disease that attacks the nerve cells in the brain and spinal cord. ALS causes progressive degeneration of the motor neurons, which reach from the brain to the spinal cord and from the spinal cord to the body’s muscles. “With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed,” the ALS Association website states.
As reported online in Neuron, a research team led by Dr. Bryan Traynor of the Laboratory of Neurosciences at the NIH’s National Institute on Aging (NIA) identified the mutation, which is on a single gene, C9ORF72, and occurs on the short arm of chromosome 9. “The mutation, called a hexanucleotide repeat expansion, is an unusual one that involves repeating a DNA sequence over and over again,” the NIH reported.
“This finding highlights the importance of studying isolated populations with high rates of a specific disease. Finland has the highest rates of ALS in the world,” said Dr. Story Landis, who serves as the director of NIH’s National Institute of Neurological Disorders and Stroke (NINDS). “By collecting virtually every case within the Finnish population, Traynor and colleagues were able to definitively show that this particular gene mutation plays a role in ALS development – a discovery relevant not to just that population, but critical to our basic understanding of this disorder.”
Researchers are increasingly finding that the pathologies of FTD and ALS overlap. The discovery of the 9p21 gene is the most significant to date. For example, five major genes that were previously identified in ALS familial cases accounted for approximately 26% of these cases. This newest genetic discovery increases that percentage to 65%. The scientists believe that this finding will help them gain new insights into these devastating diseases, including the interplay between the disorder’s genetic risk and other factors that trigger the onset and progression of FTD and ALS.