Presentation on theme: "Geuvadis RNAseq UNIGE Genetic regulatory variants Tuuli Lappalainen University of Geneva Geuvadis Analysis meeting II, July 11, 2012."— Presentation transcript:
Geuvadis RNAseq UNIGE Genetic regulatory variants Tuuli Lappalainen University of Geneva Geuvadis Analysis meeting II, July 11, 2012
Expression quantitative trait loci (eQTLs) T C Genotypes Expression level Works very well in cis. Difficult in trans The same principle can be applied to any quantitative phenotype with a genomic locus Statistical power only for common variants
QC – mRNA quantifications
miRNA QC POP LAB
eQTLs in Geuvadis PopNGenes with eQTL (FDR) Best eQTL indel (null 8.9%) CEU+GBR (5.1%)375 (14.4%) TSI (7.7%)242 (13.8%) FIN (7.3%)255 (14.0%) YRI (6.3%)242 (11.3%) EUR union NA ALL union NA TODO: Some methodological improvements Combine Europeans with a PC correction of pop structure Test exon versus transcript quantification Trans-analysis of large deletions didn’t yield much…
Splicing QTLs (sQTLs) in Geuvadis PopNGenes with sQTL – transcript ratio Genes with sQTL – links CEU+GBR (FDR 9.1%)1251 forward (FDR 5.6%) 1077 reverse (FDR 6.6%) nonredundant: 1949 ALL union419274NA E1E2E3 FR E1-E2 = 5 (R E1-E2 ) / 5 (R E1-E2 ) + 3 (R E1-E3 ) = FR E1-E3 = 3 (R E1-E3 ) / 5 (R E1-E2 ) + 3 (R E1-E3 ) = ALTRANS method by Halit Ongen links or junctions? counts or fractions?
Integrating transcriptome QTLs eQTLs for mRNA and miRNA exon/miRNA_quantification ~ snp + covariates sQTLs link/junction_ratio ~ snp + covariates link/junction quantification ~ snp + exon_quantification + covariates multiple tQTLs: for the same gene exon_quantification ~ snp2 + exon_eQTL_snp1 + covariates link/junction ratio ~ snp2 + exon_eQTL_snp1 + covariates targeted trans analysis exon quantification ~ mi(eQTL)_snp + covariates link/junction_ratio ~ mieQTL_snp + covariates
Functional annotation of eQTLs TODO: Direction of effect TF motifs, PWM scores Different eQTL frequencies Other tQTLs What’s the best way to tell if we have the causal variant or not? And how often do we seem to find it?
Allele specific expression A C G T C C T T T T T cis eQTL*coding SNPmRNA-sequencing Statistical testing for ASE What is the allelic ratio? Significantly different from 50-50? *or an epigenetic reason for higher expression of only one homolog in the studied cell population (e.g. imprinting)
Rare variants have higher effect sizes derived allele frequency power in eQTL analysis eQTL analysis – expected result ASE analysis ~ REGULATORY VARIANT FREQUENCY Proper quantification of the effect?
Quantifying genetic effects to individual differences TODO: More work on the ASE difference analysis Variation within/between populations Rare variant ASE mapping
Can we predict functional effects of genetic variants? How likely is an unknown variant to have regulatory effects based on known priors? Gene expression ~ variant’s : distance from TSS + position in gene + functional annotation + allele frequency + conservation score + variant type… “gene expression” could be e.g. exon quantification or link ratio (Gaffney et al Genome Biology) Does anyone have good experience of this type of modeling?
Acknowledgements The FunPopGen lab Manolis Dermitzakis Analysis Alfonso Buil Thomas Giger Halit Ongen Data processing Ismael Padioleau Alisa Yurovsky Technicians Deborah Bielsen Emilie Falconnet Alexandra Planchon Luciana Romano Stanford School of Medicine Stephen Montgomery The 1000 Genomes Consortium Functional Interpretation Group FUNDING European Union National Institute of Health Louis-Jeantet Foundation Academy of Finland Emil Aaltonen Foundation Swiss National Science Foundation NCCR