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Literature & web-database research: PubMed, Google Scholar, GWAS Catalog, PhenoScanner, Open Targets.
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Fine-mapping: FINEMAP, SuSiE, SuSiE derivatives.
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Trans-ethnic and cross-population studies: mvSuSiE, meSuSiE, SuSiEx.
- Functional annotation
- bioinformatics tools: VEP, ANNOVAR,
- databases original: ENCODE, Roadmap Epigenomics, GTEx, FANTOM5, BLUEPRINT
- derived: CADD, DeepSEA, enformer, ExPecto, DanQ, Basenji, DeepCpG.
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xQTL analysis for annotation: Open-Targets-Genetics, BloodeQTL, GTEx, BiosQTL, NBDC, Blueprint, FunGen-xQTL, and xQTL derived (EMS predictions).
- Integration of xQTL with GWAS:
- Enrichment analysis: MAGMA, FUMA, GREGOR
- Colocalization analysis: COLOC, fastENLOC, ColocBoost, PICCOLO.
- Transcriptome-wide association studies (TWAS): FUSION, UTMOST, pecotmr.
- Mendelian randomization (MR): SMR, pecotmr.
- Annotation using xQTL targets (molecular phenotypes): Using the molecular phenotypes regulated by xQTLs as annotations to investigate the functional consequences of the associated variants. This can include:
- Allele-specific expression (ASE) analysis: Assessing allele-specific expression of candidate variants, which can be considered as targets of ASE-QTLs, using databases such as AlleleDB and Blueprint to investigate the regulatory effects of the variants on gene expression. Tools: ASEP, WASP, QuASAR, MBASED, Cyp2d-ASE.
- Methylation peak analysis: Examining the effects of methylation QTLs (meQTLs) on DNA methylation peaks and patterns.
- Chromatin accessibility analysis: Assessing the effects of chromatin accessibility QTLs (caQTLs) on chromatin accessibility and open chromatin regions using eg ATAC-seq, DNase-seq, FAIRE-seq, ChiP-seq
- Splice site target analysis.
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Chromatin interaction analysis: Hi-C, Promoter Capture Hi-C (PCHi-C), and Chromosome Conformation Capture (3C) data to identify potential target genes and regulatory elements.
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In silico analysis of transcription factor binding: Assessing the allele-specific effects of candidate SNPs on transcription factor binding. eg msCENTIPEDE, DeepBind.
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Deep learning-based variant function prediction: DeepSEA, ExPecto, DanQ, Basenji, DeepCpG, enformer.
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SNP-to-Gene linking strategies: Utilizing SNP-to-Gene linking strategies such as Locus-to-Gene (L2G) and cis-expression Structural Gene (cS2G) to prioritize candidate causal variants at GWAS loci and identify potential target genes. Tools: FUMA, SMR, TWAS, COLOC, DEPICT, NetWAS, EpiMap.
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Functional validation using CRISPR-based gene editing: Employing CRISPR/Cas9-based gene editing techniques, such as deletion and single-base mutation, in isogenic cell lines to investigate the functional consequences of the candidate variants on gene expression and cellular phenotypes. Tools: CRISPR-Cas9, CRISPRi, CRISPRa, base editors (ABE, CBE), prime editing, CRISPR screening (GeCKO, CRISPRko, CRISPRa), CRISPR-SURF.
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Experimental validation using primary cells from patients: Assessing the functional effects of the candidate variants in primary cells, such as B-cells, T-cells, and monocytes, collected from individuals with the disease (e.g., SLE) and healthy controls, representing diverse sexes and ethnicities, to validate the findings from cell line experiments. Methods: FACS, magnetic cell separation, single-cell RNA-seq, ATAC-seq, ChIP-seq, bisulfite sequencing, proteomics, metabolomics.
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Cellular phenotype analysis: Characterizing the effects of the candidate variants on cellular phenotypes related to the disease, such as autophagy, apoptosis, proliferation, and endosomal pH, using various experimental techniques, including qRT-PCR, Western blot, immunofluorescence, flow cytometry, and transmission electron microscopy. Tools: ImageJ, CellProfiler, FlowJo, GraphPad Prism, R, Python.
- siRNA-based knockdown or overexpression: Employing siRNA-based knockdown or overexpression of candidate target genes in wild type, SNP-knockout, and SNP-base edited isogenic cell lines to assess the contribution of individual target genes to the observed cellular phenotypes. Tools: Lipofectamine, RNAiMAX, Dharmafect, Accell, HiPerFect, TransIT-X2, Polyplus-transfection.