Dataset Information

Evidence for a novel late-onset Alzheimer disease locus on chromosome 19p13.2.

ABSTRACT: Late-onset familial Alzheimer disease (LOFAD) is a genetically heterogeneous and complex disease for which only one locus, APOE, has been definitively identified. Difficulties in identifying additional loci are likely to stem from inadequate linkage analysis methods. Nonparametric methods suffer from low power because of limited use of the data, and traditional parametric methods suffer from limitations in the complexity of the genetic model that can be feasibly used in analysis. Alternative methods that have recently been developed include Bayesian Markov chain-Monte Carlo methods. These methods allow multipoint linkage analysis under oligogenic trait models in pedigrees of arbitrary size; at the same time, they allow for inclusion of covariates in the analysis. We applied this approach to an analysis of LOFAD on five chromosomes with previous reports of linkage. We identified strong evidence of a second LOFAD gene on chromosome 19p13.2, which is distinct from APOE on 19q. We also obtained weak evidence of linkage to chromosome 10 at the same location as a previous report of linkage but found no evidence for linkage of LOFAD age-at-onset loci to chromosomes 9, 12, or 21.

SUBMITTER: Wijsman EM

PROVIDER: S-EPMC1182019 | biostudies-literature | 2004 Sep

REPOSITORIES: biostudies-literature

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Evidence for a novel late-onset Alzheimer disease locus on chromosome 19p13.2.

Wijsman Ellen M EM Daw E Warwick EW Yu Change-En CE Payami Haydeh H Steinbart Ellen J EJ Nochlin David D Conlon Erin M EM Bird Thomas D TD Schellenberg Gerard D GD

American journal of human genetics 20040708 3

Late-onset familial Alzheimer disease (LOFAD) is a genetically heterogeneous and complex disease for which only one locus, APOE, has been definitively identified. Difficulties in identifying additional loci are likely to stem from inadequate linkage analysis methods. Nonparametric methods suffer from low power because of limited use of the data, and traditional parametric methods suffer from limitations in the complexity of the genetic model that can be feasibly used in analysis. Alternative met ...[more]

PMID: 15248153

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Project description:Genome-wide association studies (GWAS) of late-onset Alzheimer disease (LOAD) have consistently observed strong evidence of association with polymorphisms in APOE. However, until recently, variants at few other loci with statistically significant associations have replicated across studies. The present study combines data on 483,399 single nucleotide polymorphisms (SNPs) from a previously reported GWAS of 492 LOAD cases and 496 controls and from an independent set of 439 LOAD cases and 608 controls to strengthen power to identify novel genetic association signals. Associations exceeding the experiment-wide significance threshold (alpha=1.03x10(-7)) were replicated in an additional 1,338 cases and 2,003 controls. As expected, these analyses unequivocally confirmed APOE's risk effect (rs2075650, P=1.9x10(-36)). Additionally, the SNP rs11754661 at 151.2 Mb of chromosome 6q25.1 in the gene MTHFD1L (which encodes the methylenetetrahydrofolate dehydrogenase (NADP+ dependent) 1-like protein) was significantly associated with LOAD (P=4.70x10(-8); Bonferroni-corrected P=0.022). Subsequent genotyping of SNPs in high linkage disequilibrium (r2>0.8) with rs11754661 identified statistically significant associations in multiple SNPs (rs803424, P=0.016; rs2073067, P=0.03; rs2072064, P=0.035), reducing the likelihood of association due to genotyping error. In the replication case-control set, we observed an association of rs11754661 in the same direction as the previous association at P=0.002 (P=1.90x10(-10) in combined analysis of discovery and replication sets), with associations of similar statistical significance at several adjacent SNPs (rs17349743, P=0.005; rs803422, P=0.004). In summary, we observed and replicated a novel statistically significant association in MTHFD1L, a gene involved in the tetrahydrofolate synthesis pathway. This finding is noteworthy, as MTHFD1L may play a role in the generation of methionine from homocysteine and influence homocysteine-related pathways and as levels of homocysteine are a significant risk factor for LOAD development.

Dataset Information

Evidence for a novel late-onset Alzheimer disease locus on chromosome 19p13.2.

Publications

Evidence for a novel late-onset Alzheimer disease locus on chromosome 19p13.2.

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