[A version of this item appears in: Dementia: the Latest Evidence Newsletter (RWHT), Volume 1 Issue 10, May 2011].
Five further genes which increase the risk of developing late-onset Alzheimer’s Disease have been identified, taking the number of identified genes linked to Alzheimer’s to 10. The disease is thought to be up to 80% genetic. If the effects of all 10 genes could be eliminated then the risk of developing the disease might be cut by 60%.
The new genes affect three bodily processes and could become targets for treatment, although new treatments could be 10 – 15 years away.
Genes in Alzheimer’s Disease
The three bodily processes involve: (1) the way fat and cholesterol are processed; (2) the mechanism by which brain cells process large molecules (endocytosis); and (3) the immune system.
Immune system genes: CLU, CR1, ABCA7, CD33 and EPHA1.
Fat processing genes: APOE, CLU and ABCA7.
Cell membrane genes: PICALM, BIN1, CD33 and CD2AP.
There are likely to be other genes contributing to the disease. Some commentators say these findings should be interpreted carefully because the particular genetic variants identified are not necessarily the cause of Alzheimer’s disease. They may, instead, lie close to functioning genes that have negative effects. More research needed.
Gallagher, J. (2011). Five more Alzheimer’s genes discovered, scientists say. London: BBC Health News, April 4th 2011.
More genetic clues to Alzheimer’s found. London: NHS Choices, April 4th 2011.
The original scientific articles:
Naj, AC. Jun, G. [and] Beecham, GW. [et al] (2011). Common variants at MS4A4/MS4A6E, CD2AP, CD33 and EPHA1 are associated with late-onset Alzheimer’s disease. Nature Genetics, 2011. Published online April 3rd 2011. (Click here to view the PubMed abstract).
The first study confirmed previously known associations on genes called CR1, CLU, BIN1 and PICALM. It also identified four new genetic variants that were more common in people with Alzheimer’s disease. These were variants on genes called MS4A4 / MS4A6E, CD2AP, CD33 and EPHA1.
Hollingworth, P. Harold, D. [and] Sims, R. [et al] (2011). Common variants at ABCA7, MS4A6A/MS4A4E, EPHA1, CD33 and CD2AP are associated with Alzheimer’s disease. Nature Genetics, 2011. Published online April 3rd 2011. (Click here to view the PubMed abstract).
The second study confirmed that four of the genetic variants identified in study one were associated with Alzheimer’s disease. They also identified a fifth genetic variant on gene ABCA7.