Journal Article

Fine-Mapping, Gene Expression and Splicing Analysis of the Disease Associated LRRK2 Locus

Heutink, Peter, Ryten, Mina, Hernandez, Dena, Trabzuni, Daniah, Lewis, Patrick A., Plagnol, Vincent, Sharma, Manu, Cai, Huaibin, Hardy, John, Emmett, Warren, Zeller, Tanja, Vandrovcova, Jana, Nalls, Michael A., de Silva, Rohan, Schadt, Eric, Walker, Robert, Ramasamy, Adaikalavan, Garnier, Sophie, Lesage, Suzanne, Wood, Nicholas W., Singleton, Andrew, Smith, Colin, Brice, Alexis, Simon-Sanchez, Javier, Mamais, Adamantios, Bandopadhyay, Rina, Lackner, Karl J., Weale, Michael E., Gasser, Thomas

2013

Overview

Association studies have identified several signals at the LRRK2 locus for Parkinson's disease (PD), Crohn's disease (CD) and leprosy. However, little is known about the molecular mechanisms mediating these effects. To further characterize this locus, we fine-mapped the risk association in 5,802 PD and 5,556 controls using a dense genotyping array (ImmunoChip). Using samples from 134 post-mortem control adult human brains (UK Human Brain Expression Consortium), where up to ten brain regions were available per individual, we studied the regional variation, splicing and regulation of LRRK2. We found convincing evidence for a common variant PD association located outside of the LRRK2 protein coding region (rs117762348, A>G, P = 2.56×10(-8), case/control MAF 0.083/0.074, odds ratio 0.86 for the minor allele with 95% confidence interval [0.80-0.91]). We show that mRNA expression levels are highest in cortical regions and lowest in cerebellum. We find an exon quantitative trait locus (QTL) in brain samples that localizes to exons 32-33 and investigate the molecular basis of this eQTL using RNA-Seq data in n = 8 brain samples. The genotype underlying this eQTL is in strong linkage disequilibrium with the CD associated non-synonymous SNP rs3761863 (M2397T). We found two additional QTLs in liver and monocyte samples but none of these explained the common variant PD association at rs117762348. Our results characterize the LRRK2 locus, and highlight the importance and difficulties of fine-mapping and integration of multiple datasets to delineate pathogenic variants and thus develop an understanding of disease mechanisms.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Aging / Alternative Splicing / Analysis / Bioinformatics / Biology / Blood & organ donations / Brain / Brain - metabolism / Brain - pathology / Brain research / Cerebellum / Coding / Confidence intervals / Consortia / Cortex / Crohn Disease - genetics / Crohn's Disease / Development and progression / Exons / Forensic pathology / Gene expression / Gene Expression Profiling / Gene Expression Regulation / Gene mapping / Genetic Association Studies / Genetic engineering / Genetics / Genomes / Genomics / Genotyping / Hospitals / Humans / Kinases / Laboratories / Leprosy / Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 / Life Sciences / Linkage disequilibrium / Liver / LRRK2 protein / Male / Mapping / Medical research / Medicine / Molecular modelling / Monocytes / Movement disorders / Mutation / Neural coding / Neurodegenerative diseases / Neurology / Neuropathology / Neurosciences / Parkinson Disease - genetics / Parkinson's disease / Pathogenesis / Polymorphism, Single Nucleotide / Protein Serine-Threonine Kinases - genetics / Quantitative genetics / Quantitative Trait Loci / Ribonucleic acid / RNA / RNA sequencing / RNA, Messenger - genetics / RNA, Messenger - metabolism / Single-nucleotide polymorphism / Splicing