Oct. 31 --
THURSDAY, Oct. 30 (HealthDay News) -- Four newly identified genes may be linked to the most common form of late-onset Alzheimer's disease, U.S. researchers report.
The team, from Massachusetts General Hospital-MassGeneral Institute for Neurological Disease (MGH-MIND), Boston, conducted a gene scan of hundreds of families with a history of the devastating neurological disorder.
They first tested about a half million DNA markers in samples collected from more than 400 families in which at least three members had Alzheimer's disease.
The analysis revealed five markers exhibiting genetic associations with Alzheimer's. One of those genes was APOE, the only gene proven to increase risk for late-onset Alzheimer's disease.
To confirm the four new markers, the researchers analyzed samples from 900 additional families with a history of Alzheimer's. The strongest marker was located on chromosome 14.
"The genetic association of Alzheimer's with this novel chromosome 14 gene, which like APOE appears to influence age of onset, is sufficiently strong to warrant intensive follow-up investigations into its role in the process of nerve cell death in this disease," study leader Rudolph Tanzi, director of the genetics and aging research unit at the Boston institute, said in an MGH news release.
Another of the newly-identified markers is a gene known to cause a movement disorder called spinocerebellar ataxia, which involves the death of nerve cells in other parts of the central nervous system. The other markers are a gene involved in the innate immune system (part of the body's defense against bacteria and viruses) and a gene that produces a synaptic protein.
The findings, which appear online and in the Nov. 7 print issue of the American Journal of Human Genetics, are the first results of the Alzheimer's Genome Project, which is supported by the Cure Alzheimer's Fund and the U.S. National Institutes of Mental Health.
"Virtually all current research into therapies is based on the Alzheimer's genes that we already know about; so each new gene we find not only enhances our ability to predict and diagnose the disease, but also provides valuable new clues about biochemical events and pathways involved in the disease process," Tanzi said.
The U.S. National Institute on Aging has more about Alzheimer's disease genetics.
SOURCES: Massachusetts General Hospital, news release, Oct. 30, 2008