“For any given individual, for a given age and genetic information, we can calculate your personalized annualized risk for developing AD,” Dr. Desikan.
THE STUDY looked at genetic data from over 70,000 Alzheimer’s Disease (AD) patients and normal elderly controls. Data was obtained from various projects including the Alzheimer’s Disease Genetics Consortium, the National Alzheimer’s Coordinating Center and the Alzheimer’s Disease Neuroimaging Initiative.
THE TEAM encompassed global researchers piloted by the University of California San Diego School of Medicine and University of California San Francisco. Rahul Desikan, M.D., Ph.D. (UCSF) and Chun-Chieh Fan, M.D. (UCSD) co-led the investigation.
THE FINDINGS resulted in a Polygenic Hazard Scoring (PHS) system based on Single Nucleotide Polymorphisms (SNPs) linked to AD and APOE status. E4 variations in the APOE gene are known to be at greater risk of developing late-onset AD.
High PHS scores represented persons with the highest yearly AD incidence rate at a younger age (10-15 years earlier than those with low PHS scores).
PHS identified people at a cognitively normal baseline but eventually developed AD
PHS strongly predicted empirical age of AD onset and progression from normal aging to AD, with strongly associated neuropathology and biomarkers of AD neurodegeneration
“From a clinical perspective, the polygenic hazard score provides a novel way not just to assess an individual’s lifetime risk of developing AD, but also to predict the age of disease onset,” said senior author Anders Dale, PhD, director of the Center for Translational Imaging and Precision Medicine and professor in neurosciences, radiology, psychiatry and cognitive science at UC San Diego School of Medicine. “Equally important, continuous polygenic testing of AD genetic risk can better inform prevention and therapeutic trials and be useful in determining which individuals are most likely to respond to therapy.”
THE APPLICATION of PHS in a score can aid in early diagnosis of AD and help in determining patient prognosis. It additionally is helpful in identifying at risk patients for those that do not have the APOE E4 allele, the most important genetic risk factor for AD at this time.
THE LIMITATIONS of the study included the lack of representation of African-American or Latino populations. The study was primarily composed of European decent participants. According to study co-lead Dr. Fan, this was due to the fact that only one of the cohorts of study participants met critical mass in order to derive the required amount of data needed. Dr. Fan believe that these disparities will be removed as genome studies increase worldwide.
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More information: PLOS Medicine, DOI: 10.1371/journal.pmed.1002258
Journal reference: PLoS Medicine
Provided by: University of California – San Diego
Diagram of the brain of a person with Alzheimer’s Disease. Credit: Wikipedia/public domain.
Read more at: https://medicalxpress.com/news/2017-03-genetic-age-associated-alzheimer-disease.html#jCp
Findings from this new study were published recently in PLOS Medicine in an article entitled “Genetic Assessment of Age-Associated Alzheimer Disease Risk: Development and Validation of a Polygenic Hazard Score.”