Year of Publication

2009

Degree Name

Doctor of Philosophy (PhD)

Document Type

Dissertation

College

Medicine

Department

Physiology

First Advisor

Dr. Steven Estus

Abstract

Since apoE allele status is the predominant Alzheimers disease (AD) genetic risk factor, functional single nucleotide polymorphisms (SNPs) in brain apoE receptors represent excellent candidates for association with AD. Therefore, three low density lipoprotein receptor (LDLR) SNPs were evaluated by TaqMan allelic discrimination assays for association with AD and I found that certain haplotypes alter the odds of AD. A SNP within LDLR exon 12, rs688, was identified in silico as neutralizing a putative exon splicing enhancer (ESE). Since LDLR is a major apoE receptor in the brain, I hypothesized that rs688 modulates LDLR splicing in neural tissues and associates with AD. To evaluate this hypothesis, I analyzed splicing patterns in human hippocampus samples and established that this SNP was associated with significantly decreased LDLR exon 12 splicing efficiency when the minor allele T is present in vivo. Lastly, I evaluated whether rs688 associates with AD by genotyping DNA from the Religious Orders Study (ROS) series. The rs688T/T genotype was associated with increased AD odds in males, but not in females, in a dataset consisting of 1,457 men and 2,055 women drawn from three case-control series. The rs688T/T genotype was associated with increased AD odds in males (recessive model, odds ratio (OR) of 1.49, 95% confidence interval (CI) of 1.13- 1.97, uncorrected p=0.005), but not in females. In summary, these studies identify a functional apoE receptor SNP that is associated with AD in a sex-dependent fashion.

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