We will use a combination of second and third generation deep sequencing of selected candidate regions, whole exomes and mRNAs to identify both common and uncommon variants that predispose to PBC susceptibility. The sequencing of selected chromosome regions in 150 cases and 150 controls will target identification of variants that underlie the association of IL12A, SPIB, and a chromosome 17 locus (IKZF3/ORMDL3) that are identified in our PBC GWAS. The paired sequencing of these regions will provide the opportunity to ascertain coding and non-coding variation including copy number variants. The exome sequencing of 400 cases and 400 controls will screen for uncommon genetic variants that are not amenable to GWAS detection and provide the opportunity to test an alternate paradigm that does not depend on the common variant hypothesis. Importantly, mRNA sequencing of two cell populations implicated in PBC pathogenesis (CD8+ and CD4+ T cells) will complement both the chromosome region and exome results. For this aspect, mRNA will be sequenced in 75 cases and 75 controls. This mRNA sequencing together with the targeted chromosomal region sequencing and exome sequencing will provide the ability to correlate sequence variation with 1) gene expression, 2) eQTN data, 3) alternative exon usage, 4) RNA editing and 5) preferential allelic expression. A variety of informatics approaches using the combined data will establish a prioritization of SNPs for validation and testing in large numbers 1100 PBC cases and 2200 controls (not including discovery subject set) using a Golden Gate 1536 SNPlex. Both the sequencing and replication studies will be performed using a homogeneous Italian population. Together this design should maximize our ability to identify uncommon as well as more common variants that are important in the etiopathogenesis of this autoimmune disease.

Public Health Relevance

The goal of this proposal is to identify causal genetic variants underlying the risk for primary biliary cirrhosis. Primary biliary cirrhosis is considered a model autoimmune disease and defining the genetic basis of immunopathology will not only help patients with this disease, but will also be generically important for autoimmunity. The study will utilize the recent advances in technology to provide DNA sequence differences and an opportunity to link genetic variation to functional changes import in the susceptibility of this disease with high morbidity and mortality. These studies will provide valuable insight into the pathogenesis of PBC that may lead to therapeutic development.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01DK091823-04
Application #
8728832
Study Section
Genomics, Computational Biology and Technology Study Section (GCAT)
Program Officer
Karp, Robert W
Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of California Davis
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Davis
State
CA
Country
United States
Zip Code
95618
Carbone, Marco; Lleo, Ana; Sandford, Richard N et al. (2014) Implications of genome-wide association studies in novel therapeutics in primary biliary cirrhosis. Eur J Immunol 44:945-54
Bianchi, Ilaria; Carbone, Marco; Lleo, Ana et al. (2014) Genetics and epigenetics of primary biliary cirrhosis. Semin Liver Dis 34:255-64
Selmi, Carlo; Cavaciocchi, Francesca; Lleo, Ana et al. (2014) Genome-wide analysis of DNA methylation, copy number variation, and gene expression in monozygotic twins discordant for primary biliary cirrhosis. Front Immunol 5:128
Kar, S P; Seldin, M F; Chen, W et al. (2013) Pathway-based analysis of primary biliary cirrhosis genome-wide association studies. Genes Immun 14:179-86
Badolato, Raffaele; Prandini, Alberto; Caracciolo, Sonia et al. (2012) Exome sequencing reveals a pallidin mutation in a Hermansky-Pudlak-like primary immunodeficiency syndrome. Blood 119:3185-7