Dementia News & Events

Researchers have discovered two more important genetic links to late onset Alzheimer's.

The first gene associated with late onset Alzheimer's disease was ApoE4, discovered in 1994.  In January, 2007, Columbian University Medical Centre announced the discovery of a second such gene.  A team of 41 researchers from 15 international facilities, including Columbia School of Medicine, the University of Toronto, and the University of Boston, examined the relationship of a gene called SORL1 to Alzheimer's in four ethnic groups (Hispanic, African-American, Israeli-Arab and Caucasian).

At the University of Toronto, Dr. Peter St. George Hyslop's team focused on the part of the genome where SORL1 was found. Previous research had found a connection between Alzheimer's and amyloid precursor protein (APP) processing.  APP is the large protein from which the toxic amyloid proteins arises. The Columbia team decided to focus their study on genes associated with APP.  Their experiments showed that when SORL1 is not working properly, it sends APP down a pathway that increases the production of amyloid beta (Aβ) peptides in the brain, causing Alzheimer's disease.  In short, when SORL1 is working properly, Aβ is recycled in a non-toxic form.

In 1994, when Dr. Richard Mayeux from the University of Columbia began to notice the high incidence of Alzheimer's in the Hispanic Dominican population of Manhattan.  Dr. Mayeau connected with colleagues at the University of Toronto to establish a study group of 350 Dominican families.  From there, the study expanded to include African American siblings and Israeli-Arabs through the University of Boston.  The Mayo Clinic provided data on Caucasian Alzheimer's patients.  Over five years, the researchers sampled the DNA of 6000 individuals.  The team then began work to pinpoint malfunctioning SORL1.

June 2007 update:
Most recently, in June 2007, researchers from seven organizations, including the Translational Genomics Research Institute, Banner Alzheimer's Institute, and Kronos Science Laboratory, found a linnk between gene GAB2 and late onset Alzheimer's.  Their study suggests that GAB2 prevents brain cells from tangling, a behaviour associated with Alzheimer's.  The team screened DNA from 1400 individuals with Alzheimer's.

The studies are hoped to enable both preventative and treatment therapies, and to improve diagnostic testing.

For more information, please see references below:

1. New Gene Uncovered For Late-onset Alzheimer's: Findings Replicated In Four Different Ethnic Groups. January 15, 2007 http://www.sciencedaily.com/

2. The neuronal sortilin-related receptor SORL1 is genetically associated with Alzheimer's disease. Rogaeva E, Meng Y, Lee JH, Gu Y, Kawaria T, Zou F, Katayama T, Baldwin CT, Cheng R, Hasegawa H, Chen F, Shibata N, Lunetta KL, Pardossi-Piquard R, Bohm C, Wakutani Y, Cupples LA, Cenco KT, Green RC, Pinessi L, Rainero I, Sorbi S, Bruni A, Duara R, Friendland RP, Inzelberg R, Hampe W, Bujo H, Song YQ, Anderson OM, Willnow TE, Graff-Radford N, Peterson RC, Dickson D, Der SD, Fraser PE, Schmitt-Ulms G, Younkin S, Mayeux R, Farrer LA, St George-Hyslop P. Nat Genet 2007 Feb;39(2):168-77 Epub 2007 Jan14

3. New Gene Uncovered For Late Onset Alzheimer's Findings Replicate in Four Different Ethnic Groups; Caribbean-Hispanics, Northern Europeans, African-Americans & Israeli-Arabs. January 14, 2007 http://www.cumu.columbia.edu/

4. GAB2 Alleles Modify Alzheimer's Risk in APOE varepsilon4 Carriers. Reiman EM, Webster JA, Myers AJ, Hardy J, Dunckley T, Zismann VL, Josphipura KD, Pearson JL, Hu-Lince D, Huentelman MJ, Craig DW, Coon KD, Liang WS, Herbert RH, Beach T, Rohrer KC, Zhao AS, Leung D, Bryden L, Marlowe L, Kaleem M, Mastroeni D, Grover A, Heward CB, Ravid R, Rogers J, Hutton ML, Melquist S, Petersen RC, Alexander GE, Caselli RJ, Kukull W, Papassotiropoulos A, Stephan DA, Neuron. 2007 June 7;54(5):713-720.