Webcast: Genome-Wide Association Analysis Reveals Putative Alzheimer's Disease Susceptibility Loci in Addition to APOE

Presenter: Christoph Lange, PhD., Harvard University School of Public Health

Date: December 2, 2008

Duration: 45 Minutes

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Abstract

Alzheimer's disease (AD) is a genetically complex and heterogeneous disorder. To date four genes have been established to either cause early-onset autosomal-dominant AD (APP, PSEN1, and PSEN2) or to increase susceptibility for late-onset AD (APOE). However, the heritability of late-onset AD is as high as 80% and much of the phenotypic variance remains unexplained to date. We performed a genome-wide association (GWA) analysis using 484,522 single-nucleotide polymorphisms (SNPs) on a large (1,376 samples from 410 families) sample of AD families of self-reported European descent. We identified five SNPs showing either significant or marginally significant genome-wide association with a multivariate phenotype combining affection status and onset age.

One of these signals (p= 5.7 x 10-14) was elicited by SNP rs4420638 and probably reflects APOE-ε4, which maps 11 kb proximal (r2 = 0.78). The other four signals were tested in three additional independent AD family samples composed of nearly 2700 individuals from almost 900 families. Two of these SNPs showed significant association in the replication samples (combined p values 0.007 and 0.00002). The SNP (rs11159647, on chromosome 14q31) with the strongest association signal also showed evidence of association with the same allele in GWA data generated in an independent sample of ~1,400 AD cases and controls (p = 0.04). Although the precise identity of the underlying locus(i) remains elusive, our study provides compelling evidence for the existence of at least one previously undescribed AD gene that, like APOE-ε4, primarily acts as a modifier of onset age.

About the Presenter

Dr. Christoph Lange is an Associate Professor of Biostatistics at Harvard University's School of Public Health. His current research interests fall into the broad areas of statistical genetics and generalized linear models. Recent topics in statistical genetics include family-based association tests, meta-analysis of linkage studies, GEE-methods in linkage analysis and marker-assisted selection. In the area of family-based association tests (FBATs), he has focused on the development of power calculations for family-based association studies, multivariate extensions of the FBAT statistic, FBATs for time-to-onset data and approaches to handle the multiple testing problem in family-based studies. Dr. Lange is also involved in collaborative research in asthma genetics and COPD genetics.