Gene Mutation Linked to Alzheimer’s Disease

Two research studies released yesterday shed some interesting new light on Alzheimer’s disease. A newly discovered and rare gene mutation has been found to play a role in the risk of developing Alzheimer’s. The mutated gene, TREM2 was discovered by a privately held research facility, deCODE Genetics. Looking at nearly 2,300 Icelandic participants deCODE sequenced their genes, looking for variations that were related to protein function. The study's focus was how gene variations acted in participants with healthy brains and those with Alzheimer’s disease. They concluded that one particular gene variation, TREM2 increased the risk of Alzheimer’s development in those who carried it. As if sharing a form of ESP, University College London researchers were beginning their own study that would also lead them to TREM2. These researchers wanted to dig deeper in a strange and new rare disease. This rare condition carried very odd symptoms including an unusual form of dementia and highly-fragile bones, known as sclerosis leukoencephalopathy. With the small participant population they had, as the disease is extremely rare, the researchers were able to identify one commonality between all of the individuals, the TREM2 gene. Many of these individuals had dual copies of the gene, meaning they received a mutated copy from both their mother and their father. The University College London researchers set out to find participants that carried only one copy of the mutation, to compare their findings. When they did find these people, it became quickly apparent that those with at least one copy of the mutated gene were more likely to be afflicted with Alzheimer’s disease. To back up their findings, they checked genetic data collected by researchers from all over, sure enough, the mutation was there in 1-2% of Alzheimer’s cases. TREM2 is believed to interfere with natural immune processes in the body to remove and handle the beta amyloid and plaques that are the cause of Alzheimer’s disease. Additionally, it is believed that the TREM2 mutation affects cases of Alzheimer’s dementia that occur in late life. While originally not a main focus of research, brain inflammation and its role in the disease will be paramount. TREM2 affects the proteins on a series of cells that run around the body’s systems cleaning up gunk. Since TREM2 inhibits these clean-up cells, new research will check if the brain can still adequately remove the protein toxins left by the beta amyloid without these housekeeping cells assistance. While the collective total of Alzheimer’s cases caused by this gene mutation doesn’t seem high, the fact remains that this particular gene mutation increases the development risk anywhere between 3-5 times. Additionally, 1% of the general population carries this rare gene, which again seems like a small number but is actually thousands and thousands of people. Both study teams are excited to continue on their research and discover what can be done to eradicate this gene, or at least make it dormant. Sources: New York Times Health - http://www.nytimes.com/2012/11/15/health/gene-mutation-that-hobbles-immune-response-is-linked-to-alzheimers.html MedPageToday - http://www.medpagetoday.com/Geriatrics/AlzheimersDisease/35958 Reuters - http://www.reuters.com/article/2012/11/14/us-alzheimers-gene-idUSBRE8AD1TF20121114