TY - JOUR T1 - Evaluation of a Genetic Risk Score to Improve Risk Prediction for Alzheimer's Disease. JF - J Alzheimers Dis Y1 - 2016 A1 - Chouraki, Vincent A1 - Reitz, Christiane A1 - Maury, Fleur A1 - Bis, Joshua C A1 - Bellenguez, Céline A1 - Yu, Lei A1 - Jakobsdottir, Johanna A1 - Mukherjee, Shubhabrata A1 - Adams, Hieab H A1 - Choi, Seung Hoan A1 - Larson, Eric B A1 - Fitzpatrick, Annette A1 - Uitterlinden, André G A1 - De Jager, Philip L A1 - Hofman, Albert A1 - Gudnason, Vilmundur A1 - Vardarajan, Badri A1 - Ibrahim-Verbaas, Carla A1 - van der Lee, Sven J A1 - Lopez, Oscar A1 - Dartigues, Jean-François A1 - Berr, Claudine A1 - Amouyel, Philippe A1 - Bennett, David A A1 - van Duijn, Cornelia A1 - DeStefano, Anita L A1 - Launer, Lenore J A1 - Ikram, M Arfan A1 - Crane, Paul K A1 - Lambert, Jean-Charles A1 - Mayeux, Richard A1 - Seshadri, Sudha AB -

Effective prevention of Alzheimer's disease (AD) requires the development of risk prediction tools permitting preclinical intervention. We constructed a genetic risk score (GRS) comprising common genetic variants associated with AD, evaluated its association with incident AD and assessed its capacity to improve risk prediction over traditional models based on age, sex, education, and APOEɛ4. In eight prospective cohorts included in the International Genomics of Alzheimer's Project (IGAP), we derived weighted sum of risk alleles from the 19 top SNPs reported by the IGAP GWAS in participants aged 65 and older without prevalent dementia. Hazard ratios (HR) of incident AD were estimated in Cox models. Improvement in risk prediction was measured by the difference in C-index (Δ-C), the integrated discrimination improvement (IDI) and continuous net reclassification improvement (NRI>0). Overall, 19,687 participants at risk were included, of whom 2,782 developed AD. The GRS was associated with a 17% increase in AD risk (pooled HR = 1.17; 95% CI =   [1.13-1.21] per standard deviation increase in GRS; p-value =  2.86×10-16). This association was stronger among persons with at least one APOEɛ4 allele (HRGRS = 1.24; 95% CI =   [1.15-1.34]) than in others (HRGRS = 1.13; 95% CI =   [1.08-1.18]; pinteraction = 3.45×10-2). Risk prediction after seven years of follow-up showed a small improvement when adding the GRS to age, sex, APOEɛ4, and education (Δ-Cindex =  0.0043 [0.0019-0.0067]). Similar patterns were observed for IDI and NRI>0. In conclusion, a risk score incorporating common genetic variation outside the APOEɛ4 locus improved AD risk prediction and may facilitate risk stratification for prevention trials.

VL - 53 IS - 3 U1 - http://www.ncbi.nlm.nih.gov/pubmed/27340842?dopt=Abstract ER -