Browsing by Author "Sims, Rebecca"

Background: Late Onset Alzheimer’s disease (LOAD) is the leading cause of dementia. Recent large genome-wide association studies (GWAS) identified the first strongly supported LOAD susceptibility genes since the discovery of the involvement of APOE in the early 1990s. We have now exploited these GWAS datasets to uncover key LOAD pathophysiological processes. Methodology: We applied a recently developed tool for mining GWAS data for biologically meaningful information to a LOAD GWAS dataset. The principal findings were then tested in an independent GWAS dataset. Principal Findings: We found a significant overrepresentation of association signals in pathways related to cholesterol metabolism and the immune response in both of the two largest genome-wide association studies for LOAD. Significance: Processes related to cholesterol metabolism and the innate immune response have previously been implicated by pathological and epidemiological studies of Alzheimer’s disease, but it has been unclear whether those findings reflected primary aetiological events or consequences of the disease process. Our independent evidence from two large studies now demonstrates that these processes are aetiologically relevant, and suggests that they may be suitable targets for novel and existing therapeutic approaches.

Deviations from normal body weight are observed prior to and after the onset of Alzheimer's disease (AD). Midlife obesity confers increased AD risk in later life, whereas late-life obesity is associated with decreased AD risk. The role of underweight and weight loss for AD risk is controversial. Based on the hypothesis of shared genetic variants for both obesity and AD, we analyzed the variants identified for AD or obesity from genome-wide association meta-analyses of the GERAD (AD, cases = 6,688, controls = 13,685) and GIANT (body mass index [BMI] as measure of obesity, n = 123,865) consortia. Our cross-disorder analysis of genome-wide significant 39 obesity SNPs and 23 AD SNPs in these two large data sets revealed that: (1) The AD SNP rs10838725 (pAD = 1.1 × 10−08) at the locus CELF1 is also genome-wide significant for obesity (pBMI = 7.35 × 10−09). (2) Four additional AD risk SNPs were nominally associated with obesity (rs17125944 at FERMT2, pBMI = 4.03 × 10−05, pBMI corr = 2.50 × 10−03; rs3851179 at PICALM; pBMI = 0.002, rs2075650 at TOMM40/APOE, pBMI = 0.024, rs3865444 at CD33, pBMI = 0.024). (3) SNPs at two of the obesity risk loci (rs4836133 downstream of ZNF608; pAD = 0.002 and at rs713586 downstream of RBJ/DNAJC27; pAD = 0.018) were nominally associated with AD risk. Additionally, among the SNPs used for confirmation in both studies the AD risk allele of rs1858973, with an AD association just below genome-wide significance (pAD = 7.20 × 10−07), was also associated with obesity (SNP at IQCK/GPRC5B; pBMI = 5.21 × 10−06; pcorr = 3.24 × 10−04). Our first GWAS based cross-disorder analysis for AD and obesity suggests that rs10838725 at the locus CELF1 might be relevant for both disorders.